ORIGINAL RESEARCH

Risk Factors of Ketosis in Obese Ketosis-Prone DiabeticPatients: A Case-Control Study

Li Shi . Liang Zhou . Juan Liu . Yang Ding . Xin-hua Ye .

Jin-luo Cheng

Received: January 8, 2020 / Published online: March 13, 2020� The Author(s) 2020

ABSTRACT

Introduction: Different types of ketosis-proneobese diabetic patients are seen in the clinic. Atpresent, the mechanism responsible for ketosisonset in these patients remains unclear, and wedo not know how these patients should beoptimally treated to prevent recurrent ketosis.Therefore, this study aims to investigate riskfactors of ketosis in obese ketosis-prone diabetic(OB-KPD) patients.Methods: In an observational case-controlstudy, primary OB-KPD patients [body massindex (BMI) C 28 kg/m2] were selected as the

study group (OB-KPD group), and primary obesetype 2 diabetes patients served as the controlgroup (OB-T2DM group). Clinical diagnosticassessments of fasting plasma glucose (FPG),glycated hemoglobin (HbA1c), blood lipid, areaunder curve of serum C-peptide (AUCC-P) aftersteamed bread meal, insulin sensitivity index(ISI), b-hydroxybutyric acid (b-HB) and freefatty acid (FFA) vlaues of the subjects were col-lected. Subjects in the OB-KPD group were fol-lowed up for 1 year to determine the likelihoodof insulin therapy cessation and whether ketosisrecurred by assessing clinical chemistry param-eters at 1-year follow-up.Results: Seventy-five subjects were screened, ofwhich 15 were not included in the study forseveral identified clinical reasons. On enroll-ment, the OB-KPD group displayed significantlyhigher FPG, HbA1c and FFA levels than the OB-T2DM group (p\0.01), while AUCC-P and ISIvalues were significantly lower than in the OB-T2DM group (p\0.01 and p = 0.03). Statisticalanalysis showed that increases in b-HB in theOB-KPD group were associated with increasedblood glucose and FFA and decreased AUCC-P

and ISI values. Furthermore, decreases in AUCC-

P were closely associated with increased bloodglucose values.Conclusion: The occurrence of ketosis in keto-sis-prone obese diabetic patients may be relatedto glucose and lipid metabolism disorders,increased insulin resistance and decreased b-cellsecretory functions.

Enhanced Digital Features To view enhanced digitalfeatures for this article go to: https://doi.org/10.6084/m9.figshare.11932020.

L. Shi (&) � L. Zhou � Y. Ding � X. Ye � J. Cheng (&)Department of Endocrinology, Changzhou No. 2People’s Hospital Affiliated to Nanjing MedicalUniversity, Changzhou 213164, Jiangsu, Chinae-mail: shili1204@sina.com

J. Chenge-mail: chengjinluo567@sina.com

L. ShiDepartment of Clinical Nutrition, Changzhou No. 2People’s Hospital Affiliated to Nanjing MedicalUniversity, Changzhou 213164, Jiangsu, China

J. LiuChangzhou Diabetes Institute, Changzhou 213164,Jiangsu, China

Diabetes Ther (2020) 11:965–977

https://doi.org/10.1007/s13300-020-00800-6

Trial Registration: This work was registered atthe Chinese Clinical Trial Registry with trialregistration identifier no. ChiCTR1900025909.

Keywords: Free fatty acids; Insulin sensitivityindex; Ketosis-prone diabetes; Obesity

Key Summary Points

Why carry out this study?

Different types of ketosis-prone obesediabetic patients are seen in the clinic. Atpresent, the mechanism responsible forketosis onset in these patients remainsunclear.

We do not know how these patientsshould be optimally treated to preventrecurrent ketosis.

What was learned from the study?

The occurrence of ketosis in ketosis-proneobese diabetic patients may be related toglucose and lipid metabolism disorders,increased insulin resistance and decreasedislet b-cell secretory functions.

We recommend that treatment of obeseketosis-prone diabetes should be focusedon the control of blood glucose, bloodlipid and body weight values aftercorrecting for ketosis, with the intentionof preventing the recurrence of ketosis.

INTRODUCTION

Obese individuals are at increased risk ofdeveloping type 2 diabetes because of theaccumulation of body fat, resulting in insulinresistance and hyperinsulinemia, and thedecreased use of glucose by muscles and othertissues [1]. However, different types of obesediabetic patients have been seen in the clinics inrecent years, mostly young and middle-agedmen. Most have acute onset without obviousincentives, and their disease onset is similar to

that of type 1 diabetes, which is manifested asketosis or ketoacidosis, requiring insulintreatment.

Furthermore, most patients are relieved ofsymptomology after insulin treatment and afterachieving blood glucose control on discontin-uation of insulin therapy, at which time theirislet autoantibody levels are confirmed to benegative. According to the ADA diabetes diag-nosis and classification criteria of 1997, thesepatients are obese and have negative isletautoantibody levels, being quite different fromtypical type 1 diabetes. They also have a ten-dency to present with spontaneous ketosis andhave symptoms different from typical type 2diabetes; therefore, some international investi-gators have named it atypical ketosis-pronediabetes (AKPD) or Flatbush diabetes [2].

Since these patients are experiencing dia-betes for the first time, including ketosisrequiring insulin treatment, these patients areworried that they may need long-term insulintreatment in the future, like their type 1 dia-betic patient counterparts, so they are oftenafraid and anxious.

At present, the mechanism responsible forketosis onset in OB-KPD patients remainsunclear. Therefore, some important questionsthat concern us include the following: What arethe differences in metabolic indices betweenobese ketosis-prone diabetic patients andpatients with obese type 2 diabetes? What is thecause of severe impairment of their islet func-tion? How can these patients be optimallytreated?

At present, research in this field in China andby international centers abroad comprisesmainly clinical cross-sectional and descriptivestudies, and in most cases, the measurement ofblood glucose, insulin, C-peptide and otherclinical indices is used to evaluate the level ofinsulin resistance [3, 4]. However, the HOMA-IRindex, which is calculated by fasting bloodglucose and insulin levels, might better reflectinsulin resistance of the liver, and these obesediabetic patients with ketosis are all treated withinsulin. Thus, the HOMA-IR index may notaccurately reflect the systemic insulin resistancelevel of OB-KPD patients. The recognized goldstandard for the evaluation of insulin resistance

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in China and by international standards is thehyperinsulinemic euglycemic clamp technique,which has the advantages of accurate quantifi-cation and good repeatability. However, due tothe complexity, high cost, time required andhigh demands placed on the operators of themethod, there are few groups that have devel-oped this technology in China.

Therefore, 40 obese diabetic patients of theHan nationality that first manifested as diabeteswith spontaneous ketosis in our hospital fromMarch 2016 to September 2018 were selected forthis study. The secretory function of islet b-cells,level of insulin resistance, metabolism of glu-cose and lipids, and treatment with insulin inthe early stages of the condition, and12 months after treatment, were observed. Atthe same time, 20 newly presenting obese type 2diabetic patients that visited our hospital overthe same period were selected as controls withthe aim of determining risk factors of ketosisonset and the related factors that affect thefunction of islet b-cells in OB-KPD patients ofHan ethnicity.

METHODS

Study Participants

Patients with diabetes who were 18–70 years oldand visited our hospital from March 2016 toSeptember 2018 were recruited. All patientswere recruited in concordance with the 1997ADA diagnostic criteria for diabetes [5]. Ourwork was approved by the local ethics com-mittee of the Changzhou No. 2 People’sHospital Affiliated with Nanjing MedicalUniversity with approval no. [2016] yk021-01.Our study was performed in accordance withthe Helsinki Declaration of 1964 and its lateramendments. All patients signed informedconsents before enrollment.

Grouping and Inclusion Criteria

OB-KPD GroupInclusion criteria: (1) diabetes at first onset; (2)urine ketone 2 ? (80 mg/dl) and/or an arterial

blood gas pH B 7.35; (3) BMI C 28 kg/m2; (4)measurements of glutamic acid decarboxylaseantibodies (GAD-Ab), insulin autoantibodies(IAA) and islet cell antibodies (ICA) giving anegative result.

OB-T2DM GroupInclusion criteria: (1) diabetes at first onset; (2)GAD Ab, IAA and ICA results all being negative;(3) fasting serum C peptide C 1.1 ng/ml; (4)BMI C 28 kg/m2; (5) negative urine ketonelevels. Exclusion criteria: (1) patients withstressful conditions such as infection, a surgicalprocedure and trauma, or pregnant patients; (2)patients taking medicine (such as glucocorti-coids) that affects glucose and lipid metabolismwithin 1 month of initiating therapy; (3)patients presenting with ischemic cardio-cere-brovascular disease or acute/chronic cardiacinsufficiency; (4) presentation of a special typeof diabetes mellitus such as increased bloodglucose resulting from exocrine pancreatic dis-ease or other endocrine diseases; (5) serious liverand kidney diseases [glutamic-pyruvictransaminase (GPT) levels that were 2.5-foldhigher than the upper limit of the normal ref-erence value and a serum creatininelevel C 124 lmol/l].

Research Methods

This study was an observational case-controlstudy. The normal treatment of subjects was notdisrupted or altered during the study. The clin-ical information of the selected subjects wascollected, including medical history, height,weight and blood pressure. On the 2nd daypost-admission, fasting venous blood was col-lected to measure the basic state levels of bloodglucose, HbA1c, C peptide, liver and kidneyfunction, blood lipids, FFA, b-HB, islet autoan-tibody GAD-Ab, IAA and ICA.

The standard steamed bread meal test wasused to determine the secretory function of isletb-cells. The steps were as follows: patients fastedstarting at 8:00 p.m. on the day before the test,fasting blood samples were collected frompatients at 8:00 a.m. on the test day, andsteamed bread made of 100 g flour (equivalent

Diabetes Ther (2020) 11:965–977 967

to 75 g of glucose) was eaten. Starting with thefirst bite and finishing within 15 min, venousblood was collected at 30, 60, 120 and 180 min,respectively. The levels of blood glucose (GLU)and C-peptide (C-P) were detected. The testtime of subjects in the OB-KPD group after theelimination of ketosis was confirmed.

AUCGLU ¼ GLU0 min þGLU180 minð Þ=2þ GLU30 min þ GLU60 min

þ GLU120 min;

AUCC�P ¼ C-P0 min þ C-P180 minð Þ=2þ C-P30 min

þ C-P60 min þ C-P120 min:

The criteria for the absence of islet b-cellfunction were: fasting serum C-peptide\1 ng/ml and a peak serum C-peptide\1.5 ng/ml [6].

The hyperinsulinemic euglycemic clamp testwas performed to detect the insulin sensitivityof the recruited subjects. The test time was onthe 2nd day of the standard steamed bread mealtest. The clamp system software of the EKF Co.and a Biosen glucose analyzer were used for thisexperiment. The subjects in the OB-KPD andOB-T2DM groups were fasted for 10 h, heightand weight were measured at 8:00 a.m., andthen subjects were placed in the supine positionafter defecation. A catheter with 0.9% NaClsolution was placed in the cephalic vein ormedian vein of both forearms to maintain avenous channel for blood sampling and infu-sion of various test fluids. The forearm forsampling the blood was placed in the ther-mostat (set at 50 �C) to ensure the arterializa-tion of venous blood. In the first 10 min ofclamping, the infusion of human insulin solu-tion (normal human insulin from the Novo Co.,Denmark, at 40 U/ml) at a constant dose of4 uIU/(kg-1 � min-1) was performed to rapidlyincrease the level of plasma insulin. The infu-sion was continued at a rate of 2 uIU/(kg-1 �min-1) for 140 min. During this period, thearterialization of venous blood glucose wasmeasured every 5 min, and an infusion rate of20% glucose was adjusted to make the clampblood glucose value close to the normal fastingblood glucose value of studied subjects, whichwas usually set at 5.0 mmol/l. The adjusted timewas recorded. Blood samples were collected

every 20 min to detect the plasma insulin con-centration. The glucose utilization M value inthe last 30 min was calculated.

Insulin sensitivity index ISIð Þ : ½M value

mg= kg�1 �min�1� �

=insulin concentration�

mU=Lð Þ� � 100:

Treatment of hypoglycemia and lipid-lowering in the OB-KPD group took placeduring the follow-up period. Subjects in theOB-KPD group were hospitalized for 7–10 daysand were treated with intravenous fluids,electrolytes and insulin therapy. At discharge,their treatment was a basal-bolus regimen(insulin glargine once daily and prandial pre-meal insulin aspart). If blood lipid levels werehigh, statins or fibrates were prescribed. Afterdischarge, subjects were mainly treated byoutpatient physicians from the Department ofEndocrinology and community doctors within1 year of being enrolled in the group. Theinsulin dose was adjusted according to thealgorithm shown in Fig. 1. Three months afterdischarge, if the insulin stepwise reductionprocess could not be continued, an oralhypoglycemic agent (OHA) could be usedsimultaneously; metformin is recommended asthe OHA of first choice. If blood glucose targetswere still not met, other OHAs could also beused in combination with metformin, such asacarbose, dipeptidyl peptidase-4(DDP-4)inhibitor, thiazolidinedione and sulfonylureas.

Subjects were asked to self-monitor thierblood glucose (SMBG) for at least 3 days a weekand four time per day (before three meals andbefore bed). Capillary whole-blood glucosemeasurements were performed withONETOUCH�UltraVue (LifeScan).

The follow-up assessment of subjects after1 year in the OB-KPD group comprised: 1 yearafter entering the group, the subjects in the OB-KPD group were sent to our hospital for furtherconsultation. Their weight was measured. Thefasting blood value was obtained to detectblood glucose, blood lipid and FFA levels. Thestandard steamed bread meal test and hyperin-sulinemia normal glucose clamp test were alsoperformed.

968 Diabetes Ther (2020) 11:965–977

Standard for discontinuation of insulin [7]: Ifthe blood glucose levels in the studied subjectsremained acceptable, or if hypoglycemiaoccurred when the insulin treatment dose wasvery low (\10 U/day), then under those cir-cumstances insulin was discontinued andreplaced by OHA or a simple diet treatment. Inaddition, no evidence of diabetic ketosis wasseen 1 month after insulin was discontinued.

Statistical analysis: in this study, the datawith a normal distribution were represented asmean ± standard deviation; an independentStudent’s t test was used to compare betweengroups; a paired Student’s t test was used tocompare the indicators at the time of enroll-ment with those 1 year later in the OB-KPDgroup. Non-normally distributed data wererepresented as the median and the upper andlower quartiles; the rank sum test of two inde-pendent samples was performed to comparedifferences between two groups; the rank sumtest of paired comparisons was used for pre- andpost-comparisons for intra-group differences.An alpha value of p\ 0.05 was considered astatistical difference. Multiple Pearson’s corre-lation and multiple stepwise analyses were usedto analyze the correlation among variables. The

natural logarithm was calculated for data thatwere non-normally distributed, and a correla-tion regression analysis was performed aftertransformation into a normal distribution. Theislet b-cell function and treatment effect wereanalyzed by the v2 test. All data were analyzedusing SPSS statistical analysis software program,version 19.

RESULTS

Enrollment and follow-up of subjects

Fifty-two patients in the OB-KPD group and 23patients in the OB-T2DM group were screened.Of them, 12 patients in the OB-KPD group wereexcluded (2 patients were positive for isletantibodies; 3 patients had a medical history ofpancreatitis; 6 patients were in a state of infec-tion or stress; 1 patient had a GPT level morethan twice the upper limit of normal values).Forty patients in the OB-KPD group were finallyselected. Three patients in the OB-T2DM groupwere excluded (one patient had taken drugsaffecting glucose metabolism in the past1 month, and two patients had GPT levels twicethat of the upper limit of normal values).

Fig. 1 A stepwise method for the introduction of basal-bolus insulin dose adjustment during follow-up. Atdischarge, the treatment is a basal bolus regimen (insulinglargine once daily and prandial pre-meal insulin aspart).

After discharge, the insulin dose is adjusted according tothe SMBG results and the above algorithm

Diabetes Ther (2020) 11:965–977 969

Finally, 20 patients in the OB-T2DM group wereselected.

During the 1-year follow-up period of theOB-KPD group, nine patients were lost to fol-low-up; two subjects continued insulin treat-ment and were reexamined by the standardsteamed bread meal test, and the peak valuenever exceeded 1.5 ng/ml. Five patients hadketosis that recurred during the follow-up per-iod after successful cessation of insulin therapy.Finally, we collected observation indices of theremaining 24 patients in the OB-KPD group1 year later and compared them with indices atthe time ketosis occurred 1 year before (Fig. 2).

Comparison of General InformationBetween the Two Groups

Comparison of general information betweenthe two groups was completed. The resultsshowed that the onset age for OB-KPD patientswas significantly lower than that found for OB-T2DM patients, and there was no significantdifference between the two groups in terms of

gender ratio, family history, blood pressure andBMI (Table 1).

Comparison of Blood Glucose, BloodLipids and FFA Levels between the TwoGroups

The levels of FPG, HbA1c, FFA and b-HB in theOB-KPD group were significantly higher thanthose found for the OB-T2DM group; there wasno significant difference in the levels of totalcholesterol (TCH), low density lipoproteincholesterol (LDL-C), high-density lipoproteincholesterol (HDL-C) and triglycerides (TG)between the two groups (Table 2).

Comparison of Islet b-Cell Functionand Insulin Sensitivity between the TwoGroups at Enrollment

The area under the standard post-prandialblood glucose curve in the OB-KPD group wassignificantly higher than that found in the OB-

Fig. 2 Enrollment process and follow-up of study subjects

970 Diabetes Ther (2020) 11:965–977

T2DM group (P = 0.00); AUCc-p was signifi-cantly lower than that found in the OB-T2DMgroup (P = 0.00); the insulin sensitivity indexwas significantly lower than that found for theOB-T2DM group (P = 0.03; Table 3).

Analysis of Observational Indicesin the OB-KPD Group 1 Year Post-Follow-Up

To determine the factors associated with theoccurrence of ketosis in the OB-KPD group, atthe 1-year follow-up period, we measured thelevels of blood glucose, blood lipids, FFA, islet b-cell function and ISI of 24 subjects when insulin

Table 1 Comparison of general information between the two groups

OB-KPD OB-T2DM T or v2 P

Number of patients 40 20

Age (years) 33.20 ± 9.12 40.50 ± 11.42 2.68 0.01

Gender (male/female) 34/6 13/7 3.14 0.10

Family history (yes/no) 23/17 14/6 0.88 0.41

Systolic pressure (mmHg) 134.82 ± 13.57 132.75 ± 18.69 0.49 0.63

Diastolic pressure (mmHg) 84.30 ± 11.36 86.65 ± 10.73 - 0.77 0.45

BMI(kg/m2) 30.33 ± 2.00 31.02 ± 1.85 - 1.30 0.20

Table 2 Comparison of blood glucose, blood lipids and FFA between the two groups

OB-KPD OB-T2DM T or Z P

FPG (mmol/l) 12.05 ± 3.02 9.84 ± 1.65 3.67 0.00

HbA1c (%) 12.58 ± 1.95 9.33 ± 1.50 7.14 0.00

TCH (mmol/l) 5.22 ± 1.23 5.01 ± 0.72 0.84 0.40

TG (mmol/l) 2.64 (1.71, 3.69) 2.11(1.55, 4.61) - 0.59 0.56

LDL-C (mmol/l) 2.97 ± 0.99 3.02 ± 0.64 - 0.17 0.86

HDL-C (mmol/l) 0.94 ± 0.25 1.05 ± 0.32 - 1.49 0.14

FFA (umol/l) 1156.18 ± 371.88 649.38 ± 149.92 7.49 0.00

b-HB (umol/l) 1700.58 ± 1379.52 250.65 ± 111.37 6.60 0.00

Table 3 Comparison of islet b-cell function and insulin sensitivity between the two groups at enrollment

OB-KPD OB-T2DM T P

AUCGLU 80.44 ± 14.72 72.35 ± 6.29 2.98 0.00

AUCC-P 9.06 ± 4.09 20.99 ± 11.14 - 4.64 0.00

ISI 2.43 ± 0.68 2.86 ± 0.72 - 2.24 0.03

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therapy was discontinued in the absence ofrecurrent ketosis.

As shown in Table 4, after a 1-year follow-upperiod, the levels of FPG, HbA1c, AUCGLU, TCH,TG and FFA for the studied subjects were sig-nificantly lower than was determined atenrollment; moreover, HDL-C, AUCC-P and ISIvalues were also significantly higher than hadbeen determined at enrollment. There were nosignificant differences related to LDL-C levelsand body weight.

Analysis of Factors Related to KetosisOccurrence in the OB-KPD Group

To explore the reasons for the occurrence ofketosis in the OB-KPD group, correlation anal-ysis between b-HB levels at enrollment and

levels of HbA1c, TCH, TG, HDL-C, FFA, AUCC-P

and ISI, which changed significantly in the timebetween enrollment and follow-up 1 year later,were analyzed. TG was converted to a normaldistribution by taking the natural logarithmafter pulsing 1. Results are shown in Table 5. Itwas found that b-HB was positively and statis-tically significantly correlated with HbA1c, TGand FFA and negatively correlated with AUCC-P

and ISI. No significant correlation was foundwith TCH and HDL-C. Subsequently, we per-formed a stepwise regression analysis of HbA1c,TG, FFA, AUCC-P and ISI as they were related tob-HB. The results showed that b-HB synthesismight be associated with an increase in bloodglucose and FFA and a decrease in islet secretionand insulin sensitivity. The regression equation

Table 4 Comparison of the relevant indicators in the OB-KPD group at the time of enrollment and 1 year later

At enrollment One year later T (or Z) P

FPG (mmol/l) 11.97 ± 3.01 6.88 ± 1.66 10.08 0.00

HbA1c (%) 12.75 ± 1.87 7.09 ± 1.04 13.16 0.00

AUCGLU 81.14 ± 15.47 54.31 ± 10.77 8.55 0.00

TCH (mmol/l) 5.26 ± 1.36 4.47 ± 0.93 2.56 0.02

TG (mmol/l) 2.46 (1.75, 3.81) 1.99 (1.29, 2.34) - 2.40 0.02

LDL-C (mmol/l) 2.86 ± 1.14 2.62 ± 0.73 0.90 0.38

HDL-C (mmol/l) 0.92 ± 0.22 1.01 ± 0.15 - 2.55 0.02

FFA (umol/l) 1171.08 ± 425.77 950.80 ± 261.13 3.36 0.00

AUCC-P 7.95 ± 2.79 16.38 ± 7.65 - 5.43 0.00

ISI 2.39 ± 0.73 2.93 ± 0.55 - 4.30 0.00

Body weight (kg) 92.29 ± 10.02 90.46 ± 8.46 1.86 0.08

Table 5 Correlation analysis of b-HB

HbA1c TCH TG HDL-C FFA AUCc-p ISI

b-HB

r 0.71 0.28 0.62 0.1 0.69 - 0.64 - 0.60

p 0 0.08 0 0.54 0 0 0

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was b-HB = 258.66 ? 167.14 HbA1c ? 1.26 FFA- 538.52 ISI – 88.87 AUCC-P.

Furthermore, we conducted multiple corre-lation and stepwise regression analyses onAUCC-P (Table 6). AUCC-P was negatively corre-lated with HbA1c, TG and FFA, which alsoshowed a statistical significance. Stepwiseregression analysis showed that the decrease ofislet secretion in the OB-KPD group might berelated to the increase of blood glucose. Theregression equation was AUCC-P = 25.01 - 1.27HbA1c.

Effect of Islet b-Cell Function on a CurativeEffect in OB-KPD Group Subjects

To investigate whether islet b-cell function ofsubjects in the OB-KPD group affected thecurative effect, 31 subjects who were followedup for 1 year were divided into two groupsaccording to the presence or absence of islet b-cell function at the onset of ketosis, the pres-ence and absence groups, and both wereobserved to determine whether insulin

discontinuation could be performed. As shownin Table 7, insulin discontinuation could besuccessfully performed on subjects with thepresence of islet b-cell function at the time ofonset. The results showed that patients with thepresence of islet b-cell function were more likelyto stop insulin treatment after improvement ofketosis (P = 0.02).

Influence of Altered Body Weightand Recurrence of Ketosis in the OB-KPDGroup

Among the 31 subjects in the OB-KPD groupthat completed 1-year follow-up, 29 subjectssuccessfully performed insulin discontinuationafter short-term insulin treatment. According towhether the 29 subjects had a recurrence ofketosis during follow-up, they were divided intotwo groups: a non-recurrent group (24 patients)and a recurrent group (5 patients). Body weightchanges before and after follow-up wereobserved. Observations showed that the bodyweight of subjects in the non-recurrent groupdid not significantly change before or after fol-low-up, while after 1 year the body weight ofsubjects in the recurrent group was significantlyhigher than that determined prior to enroll-ment (Table 8).

DISCUSSION

To determine the reasons for ketosis in this typeof obese diabetic patient presenting with ketosisat first onset, we selected and recruited 40 HanChinese primary obese diabetic patients withketosis in this region. The BMI of these patientswas 30.33 ± 2.00 kg/m2. Different from priorreports in China [7, 8], this study mainlyfocused on obese diabetic patients, but notoverweight AKPD patients. At the same time, 20obese type 2 diabetes patients were also selectedas the control group.

In this study, the clinical characteristics ofthe OB-KPD group were essentially consistentwith relevant reports of AKPD that were studiedboth in China and at international medicalcenters/institutes. It was found that young andmiddle-aged men were more commonly

Table 6 Correlation analysis of AUCC-P with HbA1c,TG, FFA and ISI

HbA1c TG FFA ISI

AUCC-P

r - 0.61 - 0.37 - 0.48 - 0.26

p 0 0.02 0 0.11

Table 7 Effect of islet b-cell function on whether insulindiscontinuation could be performed after improving thecondition in the OB-KPD group

Whether insulin treatment canbe discontinued after ketosis isimproved

P

No Yes

Islet b-cell function

Absence group 2 3 0.02

Presence group 0 26

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affected, and the age of onset was lower thanthat found for type 2 diabetes; most patientshad a family history of diabetes; and there wasevidence of serious glucose and lipid metabo-lism disorders at the time of onset. In addition,our study found that the blood glucose and FFAlevels of OB-KPD patients were significantlyhigher than those of OB-T2DM patients, sug-gesting that the presence of significantlyincreased blood glucose and FFA levels might beassociated with the occurrence of ketosis.

We followed up with 31 patients in the OB-KPD group for 1 year following recovery fromketosis. Two patients (6%) failed to stop insulintreatment. The standard steamed bread mealtest was reexamined with the fasting serumC-peptide\ 1 ng/ml, and the peak value wasalways \ 1.5 ng/ml. As a lack of islet b-cellfunction was evidenced, it was demonstratedthat this was A-b--ketosis-prone diabetes. Thisproportion was lower than that of a previouslypublished study of African AKPD patients byMauvais-Jarvis et al. [9], who found that 24% ofAfrican patients with ketosis tended to havetype 2 diabetes that required continuous insulintreatment—an observation that might be asso-ciated with the small number of patients in thisstudy and an observation that confirmed allpatients included in this study were indeedobese. However, any contributory confoundingby racial differences cannot be excluded.

Our study also found that for OB-KPDpatients, islet b-cell function at the onset ofketosis was very important for future treatmentplanning in these patients. Patients with resid-ual b-cell secretory function at ketosis onsetwere likely to cease insulin therapy after reliev-ing ketosis.

Ketones include acetone, acetoacetic acidand b-HB, among which b-HB is the main factor

that accounts for 78% of cases. The results ofthis study showed that the level of b-HB inpatients with ketosis in the OB-KPD groupincreased significantly. In type 1 diabeticpatients, due to the serious lack of circulatinginsulin levels, the number of islet b-cells was\10% of normal levels. Under normal conditionsof peripheral insulin sensitivity, blood sugarlevels cannot be reliably used in these patients,which leads to an increase in fat metabolism toprovide cellular energy. A large amount of fatwas metabolized to produce FFAs, which werecondensed into ketones in the liver after b-oxi-dation. The results of this study also showedthat the FFA level of the OB-KPD group wassignificantly higher than that of the OB-T2DMgroup. It is suggested that patients in the OB-KPD group also have increased fat metabolismduring a ketosis episode.

The results of this study showed that thefunction of b-cell secretion by islets wasimpaired in patients with an active ketosis epi-sode in the OB-KPD group, and the degree ofimpairment was worse than that seen inpatients in the OB-T2DM group; however, it wasunlike type 1 diabetes patients with a nearlyabsent secretory function. After improvingblood glucose in most patients, the secretoryfunction of islet b-cells improved significantly.Previous studies also found that the peakC-peptide levels of AKPD patients during fastingand after oral glucose loading were higher thanthose of type 1 diabetic patients [10, 11].

Multiple correlation and stepwise regressionanalyses have found that impaired islet b-cellsecretion in the OB-KPD group was mainlyrelated to hyperglycemia, suggesting that highglucose toxicity induced by hyperglycemiamight account for impaired islet b-cell secretionin the OB-KPD group. Mauvais-Jarvis et al. [9]

Table 8 Body weight changes of subjects in the OB-KPD group during 1-year follow-up

Non-recurrent group (24 patients) Recurrent group (5 patients)

Beforeenrollment

Afterenrollment

T P Beforeenrollment

Afterenrollment

T P

Body weight

(kg)

92.29 ± 10.02 90.46 ± 8.47 1.86 0.08 88.00 ± 6.82 91.80 ± 8.64 - 3.41 0.03

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also found that AKPD patients were more sen-sitive to glucotoxicity, which might serve as aninitiating factor of ketosis. Rong et al. [12]found that persistent hyperglycemia and highFFA levels in obese diabetic patients could sig-nificantly reduce insulin secretion and increaseapoptosis of b-cells in the islets. Glycolipid co-toxicity might be related to the onset of ketosisin AKPD patients. However, the studies ofUmpierrez and Patel [13, 14] showed that theinsulin secretory function of AKPD patients wasnot affected by fat emulsion infusion andincreased non-esterified fatty acid levels.Therefore, the b-cells in patients in the OB-KPDgroup might be susceptible to high glucosetoxicity, but the detailed mechanism remainsunclear.

Since the extent of impaired insulin secre-tory function in the OB-KPD group was not asserious as that seen in type 1 diabetes, theunprovoked ketosis in the OB-KPD group can-not be fully explained by impaired insulinsecretion alone. To further clarify the influenc-ing factors of unprovoked ketosis in the OB-KPDgroup, 24 patients that stopped insulin treat-ment 1 year after ketosis recovery and showedno recurrence in the OB-KPD group were selec-ted. We found that the blood glucose levels,TCH, TG, HDL-C and FFA levels of thesepatients were significantly lower, while that ofAUCC-P and ISI were significantly higher thanthose found at enrollment, which suggestedthat these indicators might be related to ketosis.Through multiple correlation and stepwiseregression analyses, we found that the increasesin blood glucose levels as well as increases inFFA production and decreases in the isletsecretory function and insulin sensitivity wereall significantly related to an occurrence ofketosis in the OB-KPD group. Thus, it wasspeculated that insulin resistance was involvedin ketosis occurrence in the OB-KPD group.

In this study, the hyperinsulinemic eug-lycemic clamp test showed that patients in theOB-KPD group had severe insulin resistancewhen they were enrolled. This was significantlyhigher than that found in BMI-matched OB-T2DM patients without ketosis. This observa-tion suggested that with the exception of theobesity-induced insulin resistance that was seen

in patients in the OB-KPD group, the FFA levelsin the OB-KPD group were higher than thosefound in the OB-T2DM group, which mightfurther aggravate insulin resistance. Previousstudies have found that an increase in FFA canalter the insulin signaling pathway and induceor aggravate insulin resistance in the liver andmuscle [15].

Thus, our research leads to the speculationthat patients with ketosis-prone obese diabeteshave insulin resistance and hyperglycemia dueto obesity and an abnormal lipid metabolism,and the islet b-cells of these patients are sus-ceptible to hyperglycemia toxicity [9]. Whenthe blood glucose level is high, at least to acertain extent, the secretory function of islet b-cells obviously decreases, and the insulinsecretion is insufficient. Moreover, due to insu-lin deficiency and resistance, higher blood glu-cose, increased lipodieresis and increased FFAlevels further aggravate insulin resistance. Dueto such a vicious cycle, too many FFAs enter theliver, leading to ketosis.

In addition, insulin discontinuation wasperformed in 29 patients in the OB-KPD groupwithin 3–6 months after ketosis correction, and5 of them recurred within 1 year. Comparedwith 24 patients without recurrence, these 5patients gained significant weight. Mauvais-Jarvis et al. [9] also found that the recurrence ofketosis in AKPD patients was related to weightgain, which might be a key reason accountingfor an increase in blood glucose levels. Thus, forOB-KPD patients, weight control might bebeneficial in preventing recurrent ketosis.

Study Limitations

There are some shortcomings in our research.First, due to the influence of a single-center,morbidity, enrollment conditions and patientcompliance, especially with regard the few casesenrolled and the subsequent follow-up, thesample size of this study is small. Second, thefollow-up period was only 1 year, and the timewas too short to accurately assess long-termchanges of the secretory function of islet b-cells.Third, the control group had no initial type 1diabetic ketoacidosis patients and only

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compared the differences in islet b-cell secretoryfunction between AKPD patients and type 1diabetic patients by reference to published lit-erature. Finally, there are no animal studies ormolecular biologic level research investigationsin this study. Thus, our report cannot draw aclear conclusion regarding causality, but canonly draw conclusions from the correlationanalyses and outcomes.

CONCLUSION

In conclusion, the clinical features, insulinresistance levels and significant recovery of isletb-cell secretory function after ketosis correctionshown in this study indicate that the classifi-cation of OB-KPD patients is likely to be type 2diabetes. The pathophysiologic mechanism ofspontaneous ketosis in OB-KPD patients is madeon the basis of glucose and lipid metabolic dis-orders, insulin resistance, blood glucose increa-ses and high glucose toxicity, which impair thesecretory function of islet b-cells. This results inincreased lipodieresis and FFA production,which further aggravate insulin resistance andhyperglycemia, forming a vicious circle andthus ketosis. Most patients with the presence ofislet b-cell function at the time of ketosis onsetdo not need long-term insulin-dependencetreatment. We recommend that treatment ofOB-KPD patients should be focused on thecontrol of blood glucose, blood lipid and bodyweight values after correcting for ketosis, withthe intention of preventing the recurrence ofketosis.

ACKNOWLEDGEMENTS

We thank the participants of the study.

Funding. This project was partly funded bythe Provincial innovation team DisciplineConstruction Project. The Rapid Service Fee wasfunded by the authors.

Authorship. All named authors meet theInternational Committee of Medical JournalEditors (ICMJE) criteria for authorship for this

article, take responsibility for the integrity ofthe work as a whole, and have given theirapproval for this version to be published.

Authorship Contributions. LS, LZ, XHY andJLC contributed to the conception and design ofthe study. All authors contributed to the anal-ysis or interpretation of data. LS wrote the ini-tial draft of the manuscript. All authorsreviewed and revised the manuscript. Allauthors approved the final version of themanuscript.

Disclosures. Li Shi, Liang Zhou, Juan Liu,Yang Ding, Xin-hua Ye and Jin-luo Cheng havenothing to disclose.

Compliance with Ethics Guidelines. Ourwork was approved by the local ethics com-mittee of the Changzhou No. 2 People’sHospital Affiliated to Nanjing Medical Univer-sity with approval no. [2016] yk021-01. Ourstudy was performed in accordance with theHelsinki Declaration of 1964 and its lateramendments. All patients signed informedconsent forms before enrollment.

Data Availability. The datasets during and/or analyzed during the current study are avail-able from the corresponding author on reason-able request.

Open Access. This article is licensed under aCreative Commons Attribution-NonCommer-cial 4.0 International License, which permitsany non-commercial use, sharing, adaptation,distribution and reproduction in any mediumor format, as long as you give appropriate creditto the original author(s) and the source, providea link to the Creative Commons licence, andindicate if changes were made. The images orother third party material in this article areincluded in the article’s Creative Commonslicence, unless indicated otherwise in a creditline to the material. If material is not includedin the article’s Creative Commons licence andyour intended use is not permitted by statutoryregulation or exceeds the permitted use, youwill need to obtain permission directly from thecopyright holder. To view a copy of this licence,

976 Diabetes Ther (2020) 11:965–977

visit http://creativecommons.org/licenses/by-nc/4.0/.

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