448

Review Article

Kevin M. Pantalone, DO; Charles Faiman, MD, FRCPC, MACE; Leann Olansky, MD, FACP, FACE

Submitted for publication March 1, 2011Accepted for publication April 21, 2011From the Endocrinology and Metabolism Institute, Cleveland Clinic, Cleveland, Ohio.Address correspondence to Dr. Kevin M. Pantalone, 9500 Euclid Ave, Desk F20, Cleveland, Ohio 44195. E-mail: pantalk@ccf.org, kp737502@ohio.edu. Published as a Rapid Electronic Article in Press at http://www. endocrinepractice.org on May 25, 2011. DOI:10.4158/EP11083.RACopyright © 2011 AACE.

ABSTRACT

Objective: To review the literature regarding the use of insulin glargine during pregnancy, specifically addressing the issues and concerns surrounding mitogenicity, placen-tal transfer, and maternal and fetal safety. Methods: We performed a systematic literature search using MEDLINE and BIOSIS Previews up to March 2011. Additional studies were identified by hand-searching refer-ence lists from original articles. Inclusion was limited to studies and abstracts in the English language. Results: A total of 23 reports with 1001 pregnancies managed with insulin glargine contained relevant infor-mation regarding the maternal and fetal safety of its use during pregnancy. Insulin glargine does not appear to have enhanced mitogenic activity when compared with the mitogenic activity of native human insulin. The trans-placental transfer of insulin glargine appears to be negli-gible, although it is possible that antibody-bound insulin glargine may gain access to the fetal compartment. The available data suggest that there are no identifiable, con-sistent adverse maternal or fetal outcomes with the use of insulin glargine during pregnancy, including during the first trimester.

Conclusions: Use of insulin glargine during preg-nancy should be seriously considered in uncontrolled dia-betes during pregnancy and in those patients taking insu-lin glargine before conception, because the benefits from improved glycemic control would be expected to outweigh any, as yet, unproven risks of insulin glargine exposure. (Endocr Pract. 2011;17:448-455)

Abbreviations: IGF-1 = insulinlike growth factor 1; NPH = neutral protamine Hagedorn

INTRODUCTION

Insulin glargine is a recombinant insulin analogue in which native human insulin is modified by the addition of 2 arginine residues to the C-terminus of the B-chain at position 30 and the substitution of a glycine for the aspara-gine residue at position 21 in the A-chain. These structural changes result in a prolonged duration of action when com-pared with the action of biosynthetic human insulin. Insulin glargine was first approved by the US Food and Drug Administration in April 2000, and it has dramati-cally improved the management of diabetes mellitus, par-ticularly type 1. However, its use in pregnancy has been limited, in part because it is listed as a pregnancy cate-gory C agent (animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks), but also because of concern regarding its reported mitogenic activity (1). Adequate glycemic control is often difficult to attain, particularly in type 1 diabetic patients, with the use of neu-tral protamine Hagedorn (NPH) insulin in combination with a short-acting insulin analogue. Tight glycemic con-trol is important during pregnancy, particularly in the first trimester, as hyperglycemia is a known teratogen (2), but also throughout the remainder of the pregnancy to avoid

449

macrosomia (Fig. 1) and its ensuing delivery complica-tions (4-7) and neonatal complications such as hypoglyce-mia and respiratory distress (8). Regular, NPH, lispro, and aspart insulin are all US Food and Drug Administration–assigned pregnancy cate-gory B (animal reproduction studies have failed to demon-strate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women) and are considered safe for use during pregnancy. Insulin glargine, detemir, and glulisine remain US Food and Drug Administration pregnancy category C. Data concerning the use of insulin detemir during pregnancy are limited (9-11), and to date, no data regarding glulisine are available. Over the past decade, literature has evolved regarding the safety and maternal and fetal outcomes obtained with the use of insulin glargine during pregnancy, specifically in humans, prompting the current review. This review focuses on the issues and concerns surrounding the mitogenicity of insulin glargine, the placental transfer of insulin glargine, and the literature regarding the maternal and fetal safety of insulin glargine use during pregnancy.

METHODS

A systematic literature search was conducted using MEDLINE and BIOSIS Previews up to the March 2011 time frame to review the literature regarding the use of insulin glargine during pregnancy, specifically addressing the issues and concerns of mitogenicity, placental transfer,

and maternal and fetal safety. Additional studies were identified by hand-searching reference lists from original articles. Inclusion was limited to studies and abstracts in the English language.

RESULTS

A total of 23 reports with 1001 pregnancies man-aged with insulin glargine contained relevant information regarding the maternal and fetal safety of its use during pregnancy and are summarized in this review.

Mitogenicity of Insulin GlargineMuch of the concern surrounding the use of insulin

glargine during pregnancy relates to its reported increase in mitogenic activity. Kurtzhals et al reported that insulin glargine had a 6- to 8-fold increase in insulinlike growth factor 1 (IGF-1) receptor affinity and mitogenic potency compared with that observed with native human insulin in human osteosarcoma cells (1). This finding had previ-ously been noted by sanofi-aventis as early as 1997 in their own experiments using osteosarcoma cells in which insulin glargine was reported to possess mitogenic activity 3- to 5-times higher than that of human insulin (12). In contrast, Ciaraldi et al, using skeletal muscle cells obtained from biopsy specimens of both diabetic and nondiabetic human subjects, reported that insulin glargine was equivalent to human insulin for metabolic responses and did not dis-play enhanced mitogenic activity (13). These differences

Fig. 1. The sequelae of maternal and fetal hyperglycemia/hyperinsulinemia during pregnancy. The transplacental pas-sage of maternal glucose and IgG antibody-bound insulin results in fetal hyperglycemia and hyperinsulinemia, which can cause congenital malformations, macrosomia, and neonatal complications. Figure adapted from the Pedersen hypothesis (3).

450

in mitogenicity may result from intrinsic differences in the cell lines in terms of their concentrations of IGF-1 and insulin receptors (14,15). The in vivo relevance of these in vitro mitogenicity studies is unknown, particularly since the direct effects of insulin glargine were assessed without considering the modification (degradation to 2 bioactive products M1 glargine metabolite [A21-Gly-insulin] and M2 glargine metabolite [A21-Gly-des-30B-Thr-insulin]), which is known to occur at the site of subcutaneous injection, as well as upon exposure to serum (16,17). Indeed, these bioactive metabolites of insulin glargine appear to have mitogenicity that is lower than or equal to that of human insulin, as determined using human osteosarcoma cells (1,18). Compared with that observed with human insulin, Kurtzhals et al found the IGF-1 receptor affinity and mito-genic potency of M1 to be lower, and Sommerfeld et al found both metabolites (M1 and M2) to be significantly less active in IGF-1 receptor binding and activation with equivalent mitogenicity (1,18). The potential for enhanced mitogenicity of insulin glargine vs native insulin, presumably mediated by the IGF-1 receptor, must be considered not only by taking into account the binding affinities of the ligands and their receptor activation, but also, most importantly, their con-centration differences in vivo. Insulin glargine has 0.1% of the affinity of the native ligand (IGF-1) for the IGF-1 receptor (a 1000-fold difference) (13). Moreover, there is a 1000-fold difference in terms of concentration in vivo. The serum concentration of IGF-1 is nanomolar, whereas that of insulin is picomolar. The difference in concentration at the tissue level may be significantly underestimated by the differences in serum concentrations, since IGF-1 is pro-duced not only in the liver (the principal source), but also within the target tissues, making IGF-1 appear to be both an autocrine/paracrine hormone, as well as an endocrine hormone. Thus, the IGF-1 to insulin concentration ratio at the tissue and cellular level may even be much greater than the 1000-fold difference in serum. Furthermore, the insulin concentrations that have been shown to exhibit mitogenic effects in vitro would not be expected to occur in the clini-cal setting; it was not until the insulin glargine concentra-tion reached 200 nmol/L (33 000 µIU/mL, a value 1000-fold greater than physiologic levels) that it was shown to displace more IGF-1 from its receptor than did native human insulin (13).

Placental Transfer of Insulin GlargineThe concern regarding the potential for mitogenic

effects of insulin glargine on the fetus would be moot in the absence of its transfer across the placenta into the fetal circulation. Early in vitro studies suggested that insu-lin did not cross the placenta; however, a subsequent in vitro perfusion study by Challier et al (using human pla-centa) noted the transfer of 1% to 5% of the human insulin

concentration (59 µIU/mL, 104 µIU/mL, 448 µIU/mL, and 1198 µIU/mL) in the maternal arterial blood across the pla-centa into the fetal circulation (19,20). Boskovic et al noted a small concentration-dependent transfer of insulin lispro across the placenta into the fetal circulation, but only at concentrations of 580 µIU/mL and higher (21). Pollex et al, using placentas obtained after elective cesarean delivery of uncomplicated term pregnancies, sought to determine whether insulin glargine crossed the human placenta (22). Insulin glargine was added to the maternal circulation (of the placenta) at a therapeutic/phys-iologic concentration of 150 pmol/L (~25 µIU/mL). The authors found that at these concentrations, no detectable insulin glargine was noted in the fetal circuit. Additional experiments were performed at insulin glargine concentra-tions 1000-fold higher (150 nmol/L, 225 nmol/L, and 300 nmol/L) to assess the capacity of the placenta to degrade insulin glargine at supratherapeutic levels. It was only after perfusion with such supratherapeutic/supraphysiologic concentrations (1000-fold higher; values that would not occur in the clinical setting) that insulin glargine became detectable in the fetal circuit. Even then, the rate of transfer was low. The authors concluded that insulin glargine, when used at therapeutic concentrations, as used clinically, is not likely to cross the placenta. The authors did not investigate a 10- or 100-fold higher concentration than therapeutic levels (1.5 nmol/L, 15 nmol/L), which would have been helpful to determine if these more modest supraphysiologic doses would have been sufficient enough to overcome the insulin clearance capacity of the placenta. Also, the study did not consider that the placental transfer of insulin could be different in early pregnancy, or that the placental transfer of insulin may be different in patients with diabetes mellitus (they used term placentas from healthy women). Furthermore, the study did not account for the potential antibody-medi-ated transfer of insulin across the placenta that has been reported (Fig. 1) (23). This antibody-mediated transplacen-tal transfer of insulin may be quite profound, since patients with diabetes, particularly those with type 1, may have insulin antibodies at the time of diagnosis before the start of insulin therapy (24). Furthermore, the prevalence of anti-bodies in type 1 diabetic patients treated with insulin has been reported to be quite high (mean ± standard deviation, 24.6 ± 14.2% in patients with continuous subcutaneous insulin infusion, and 13.2 ± 9.9% in patients using multiple daily injections), and the antibodies directed against native and modified insulins are cross-reactive (25,26).

Maternal and Fetal Safety of Insulin Glargine During Pregnancy

Reproduction and teratology studies in rats and rabbits showed that the effects of insulin glargine are not different from those observed with native human insulin. However, it was noted that 5 rabbit fetuses from 2 litters subjected

451

to a higher dose of insulin glargine during organogenesis exhibited dilation of the cerebral ventricles, although fer-tility and early embryonic development appeared normal (27,28). It must be recognized, however, that potential direct teratogenic effects of insulins (or other antidiabetic agents) may not be discriminated from the toxic effects of hypoglycemia. There were 3 cases of pregnancy during phase 3 clini-cal trials of insulin glargine: 1 resulted in the delivery of a healthy baby at 40 weeks’ gestation, and the other 2 preg-nancies were terminated for personal reasons (data on file from sanofi-aventis). From 2002 to 2008, the literature regarding exposure to insulin glargine during pregnancy is mainly comprised of case reports and case series (in the form of letters) and abstracts. These totaled 81 patients, mainly those with type 1 diabetes, in whom there was no apparent increase in congenital malformations or neonatal complications. Maternal glycemic control was improved without the progression or development of diabetic com-plications (Table 1) (29-40). Most of these patients were exposed to insulin glargine during the first trimester, and many continued its use throughout the duration of preg-nancy. One patient in the series reported by Tahrani et al developed retinopathy and proteinuria during pregnancy. However, she had preexisting hypertension, the control of which worsened throughout pregnancy despite antihyper-tensive therapy. In addition, during this time, her hemo-globin A1c level improved from 9.4% to 7.2%. It seems likely that the abrupt improvement in control and worsen-ing of her blood pressure control were the drivers of these adverse outcomes (39). Of the 81 reported cases, only 1 fetus, in the series reported by Ghosh et al, was born with a congenital malformation (an absent forearm) (38). There were 4 larger-scale case series on insulin glargine exposure during pregnancy published in 2006, 2008, 2009, and 2010 by Gallen et al, Di Cianni et al, Henderson et al, and Lepercq et al, respectively (Table 1) (41-44). Gallen et al noted no increase in adverse maternal outcomes although they did report cases of severe hypoglycemia (14%), early miscarriages (5%), preeclampsia (12.5%), and worsening retinopathy (6%) (41). In their study, there were no adverse fetal complications (although neonatal hypoglycemia was seen in 47%), but 3 congenital malformations/anomalies were seen (positional talipes, ventricular septal defect, and transposition of the great arteries). Di Cianni et al reported improved glycemic control during the pregnancy and 4 spontaneous abortions. In their study, no adverse fetal complications were reported, but there were 5 congenital abnormalities (2 cardiovascular, 2 genitourinary, and 1 osteoarticular) (42). The 2008 report by Di Cianni and col-leagues included the 5 cases originally reported in 2005 (32) and 2 cases reported previously and independently by 2 of the investigators (Dolci et al [31] and Caronna et al [37]) taking part in the collaboration (personal communi-cation with Dr. Graziano Di Cianni, December 2010). The

short report by Henderson et al, which contained the larg-est number of patients with type 2 diabetes mellitus, only noted that there were no perinatal deaths or instances of neonatal hypoglycemia; however, they did note a rather low incidence of macrosomia, specifically in the cohort with gestational diabetes mellitus (43). Lastly, Lepercq et al reported generally good glycemic control and the incidence of 5 spontaneous abortions, all of which were in unplanned pregnancies (44). They reported 2 cases of congenital malformations (Down syndrome in a baby born to a 40-year-old woman, which appears not to be related to either diabetes or glargine, and a case of hydrocepha-lus [cerebral hemorrhage] in an unplanned pregnancy [first trimester hemoglobin A1c level was 7.8%]), 1 stillbirth, and a 30% prevalence of large-for-gestational age births. The rate of congenital malformations in these patients with exposure to insulin glargine, mostly with type 1 diabetes, was not higher than the rate of congenital malformations observed in other population studies of patients with type 1 diabetes (45-50). However, it should be noted that there was no standard definition of congenital malformations among these reports. Nonetheless, major malformations in infants of diabetic mothers have been reported to be 4% to 10%, which is 2- to 3-fold higher than that observed in the general population (51). Thus, the use of insulin glargine during pregnancy does not appear to pose any additional risk for congenital malformations. Retrospective case-control studies describing mater-nal exposure to insulin glargine during pregnancy began to surface in 2006, mainly with NPH insulin as the compara-tor insulin. In total, 266 patients were treated with insu-lin glargine, mostly patients with pregestational diabetes mellitus (52-59). Many of these patients were exposed to glargine throughout the entire duration of their pregnancy. In general, similar maternal outcomes (safety and glycemic control) and fetal safety (no obvious association between adverse neonatal outcomes and insulin glargine) were noted (Table 1). Pöyhönen-Alho et al reported 1 case of anencephaly associated with the use of insulin glargine, as well as 1 fetal death with the use of both glargine and NPH (54). Price et al reported 2 cases of hypospadias with NPH, 2 cases of talipes (1 with glargine and 1 with NPH), and 1 case of a cleft lip with glargine (55). One prospective case-control study (abstract) reported the use of insulin glargine (n = 30) vs NPH (n = 30) or detemir insulin (n = 30) in pregnant women with type 1 diabetes (11). In general, similar maternal efficacy and safety were observed. The authors concluded that larger groups were needed to establish a relationship between fetal complications and insulin treatment; however, no congenital malformations were reported with the use of insulin glargine. Only 1 prospective study describing exposure to insu-lin glargine during pregnancy has been published (60). Negrato et al compared glargine vs NPH insulin in patients

452

Table 1Congenital Malformations in Progeny of 1001 Women Treated

With Insulin Glargine During PregnancyType of Diabetes

Authors Study design Type 1 Gestational Type 2Not

defined/otherCongenital

malformations

Devlin et al, 2002 (29) Case Report 1 0 0 0 0

Holstein et al, 2003 (30) Case Report 1 0 0 0 0

Woolderink et al, 2005 (33) Case Series 7 0 0 0 0

Graves et al, 2006 (34) Case Series 0 4 0 0 0

Kirss et al, 2006 (35) Abstract/Case Series 15 0 0 0 0

Araujo et al, 2006 (36) Abstract/Case Series 10 0 0 0 0

Ghosh et al, 2006 (38) Abstract/Case Series 17 0 0 0 1

Gallen et al, 2006 (41) Case Series 115 7 5 0 3

Torlone et al, 2007 (40) Case Series 6 0 0 0 0

Tahrani et al, 2008 (39) Case Series 13 0 0 0 0

Di Cianni et al, 2008a (42) Case Series 107 0 0 0 5

Hendersen et al, 2009 (43) Case Series 0 184 56 0 0

Lepercq et al, 2010 (44) Case Series 102 0 0 0 2

Feisullin et al, 2006 (52) Abstract/retrospective case-control: vs “other insulins”

0 0 0 15 “patients with diabetes”

0

Hothersall et al, 2006 (53) Abstract/retrospective case-control: vs NPH

0 0 0 18 “preexisting diabetes”

0

Pöyhönen-Alho et al, 2007 (54)

Retrospective case-control: vs NPH

42 0 0 0 1

Price et al, 2007 (55) Retrospective case-control: vs NPH

10 22 0 0 2

Imbergamo et al, 2008 (56) Retrospective case-control: vs NPH

15 0 0 0 0

Todorova-Ananieva and Genova, 2008 (11)

Abstract/prospective case-control: vs NPH

or detemir

30 0 0 0 0

Fang et al, 2009 (57) Retrospective case-control: vs NPH

0 15 0 37 “pregestational” 0

Egerman et al, 2009 (58) Retrospective case-control: vs NPH

0 18 0 47 “pregestational” 0

Smith et al, 2009 (59) Retrospective case-control: vs NPH

7 7 13 0 0

Negrato et al, 2010 (60) Prospective: vs NPH 0 37 0 18 “pregestational” 2

Totals NA 498 294 74 135 16

Abbreviations: NPH, neutral protamine Hagedorn. a This study included 7 cases (type 1 diabetes) previously reported by Dolci et al (n = 1) (31), Di Cianni et al (n = 5) (32), and Caronna et al (n = 1) (37) as determined via correspondence with Dr. Graziano Di Cianni (December 2010).

453

with gestational or pregestational diabetes. Patients in the pregestational cohort (n = 56 [n = 18 treated with insulin glargine]) continued their prepregnancy insulin regimen throughout the duration of their pregnancy, whereas patients in the gestational diabetes cohort (n = 82 [n = 37 treated with insulin glargine]) were randomly assigned to receive either glargine or NPH insulin. All women received insu-lin lispro as the prandial/short-acting insulin. The authors reported a decrease in maternal and neonatal adverse outcomes with insulin glargine compared with outcomes observed in the NPH insulin–treated patients. However, on examination, their statistical results did not appear to be supported by the data provided (61). Nonetheless, the use of insulin glargine was clearly not inferior to that of NPH.

Pollex et al recently conducted a systematic review and meta-analysis of all studies reporting neonatal outcomes among women with pregestational or gestational diabe-tes managed with either insulin glargine or NPH insulin during pregnancy (62). Eight studies, reporting on a total of 702 women with pregestational or gestational diabetes treated with either insulin glargine (n = 331) or NPH insu-lin (n = 371), met the inclusion criteria (42,54-60). Overall, the analysis found no differences in adverse fetal outcomes (large-for-gestational age, macrosomia, neonatal hypogly-cemia, neonatal intensive care unit admissions, shoulder dystocia, congenital anomalies, preterm delivery, perinatal mortality, hyperbilirubinemia, or respiratory distress) with the use of insulin glargine in pregnancy compared with the fetal outcomes with the use of NPH insulin. However, for each fetal outcome of interest, only a fraction of the 8 studies (between 2 and 7) provided sufficient data to be included in the analysis of any one particular outcome. The authors concluded the results of their meta-analysis may potentially improve the options for women with diabetes in pregnancy who wish to achieve excellent control of their glucose levels without the fear of adverse fetal com-plications; however, they also cautioned that future stud-ies should include a prospective randomized controlled trial design to ensure the validity of their conclusions and increase the applicability of their results (62).

Use of Insulin Glargine During LactationHuman insulin is normally present in breast milk in

tiny amounts (63,64); however, although present, systemic absorption of insulin by the neonate is not expected, as insulin is digested and destroyed by the gastrointestinal tract. It is presently unknown whether insulin glargine is excreted in human breast milk and if so, when ingested, if any neonatal adverse sequelae occur (27). Human insulin concentrations (endogenous insulin) in human milk have been reported to be 60.23 ± 41.05 µIU/mL (mean ± stan-dard deviation), as determined between 3 and 30 days post-partum in 42 mothers without diabetes who had full-term infants (65). One small study noted that breast milk from

mothers with type 1 diabetes (n = 3) contained only 15.5 µIU/mL of exogenous insulin (maternal insulin dose and insulin type were not specified) and reported no difference in breast milk insulin concentrations vs that in the breast milk of control mothers (n = 5) or mothers with type 2 diabetes (n = 5) (66). On the basis of these data, a neo-nate would have to consume more than 15 L per day to be exposed to 1 unit of insulin by mouth. In general, breast-feeding is not discouraged among mothers with diabetes, and not surprisingly, no adverse events have been associ-ated with such a practice.

CONCLUSION

The available data suggest that there are no identifi-able, consistent adverse maternal or fetal outcomes with the use of insulin glargine during pregnancy, including during the first trimester. The reported concern regarding enhanced mitogenicity with insulin glargine, compared with native insulin, noted in some, but not all, in vitro stud-ies has yet to be shown at usual physiologic doses in vivo. In addition, insulin glargine, at physiologic concentra-tions, does not appear to cross the placenta; however, anti-body-mediated transfer of insulin cannot be discounted. The totality of evidence has not revealed adverse effects (maternal or fetal) of insulin glargine use during human pregnancy. Thus, its use should be seriously considered in uncontrolled diabetes during pregnancy and in those patients taking insulin glargine before conception, because the benefits from improved glycemic control and reduced risk of hypoglycemia vs other insulin regimens (NPH) (67) would be expected to outweigh any, as yet, unproven risks of insulin glargine exposure.

DISCLOSURE

The authors have no multiplicity of interest to disclose.

REFERENCES

1. Kurtzhals P, Schäffer L, Sørensen A, et al. Correlations of receptor binding and metabolic and mitogenic poten-cies of insulin analogs designed for clinical use. Diabetes. 2000;49:999-1005.

2. Mills JL, Baker L, Goldman AS. Malformations in infants of diabetic mothers occur before the seventh gestational week. Implications for treatment. Diabetes. 1979;28:292-293.

3. Pedersen J. Weight and length at birth of infants of diabetic mothers. Acta Endocrinol (Copenh). 1954;16:330-342.

4. Ferber A. Maternal complications of fetal macrosomia. Clin Obstet Gynecol. 2000;43:335-339.

5. Grassi AE, Giuliano MA. The neonate with macrosomia. Clin Obstet Gynecol. 2000;43:340-348.

6. Spellacy WN, Miller S, Winegar A, Peterson PQ. Macrosomia--maternal characteristics and infant complica-tions. Obstet Gynecol. 1985;66:158-161.

454

7. Skyler JS, O’Sullivan MJ, Holsinger KK. The relation-ship between maternal glycemia and macrosomia. Diabetes Care. 1980;3:433-434.

8. Tyrala EE. The infant of the diabetic mother. Obstet Gynecol Clin North Am. 1996;23:221-241.

9. Sciacca L, Marotta V, Insalaco F, et al. Use of insulin detemir during pregnancy. Nutr Metab Cardiovasc Dis. 2010;20:e15-e16.

10. Lapolla A, Di Cianni G, Bruttomesso D, et al. Use of insulin detemir in pregnancy: A report on 10 type 1 diabetic women. Diabet Med. 2009;26:1181-1182.

11. Todorova-Ananieva K, Genova M. Pregnancy outcomes in women with type 1 diabetes treated with long-acting insu-lin analogues. A case control study. Abstract presented at: 44th EASD Annual Meeting of the European Association for the Study of Diabetes; September 8-11, 2008; Rome, Italy.

12. Berger M. Safety of insulin glargine. Lancet. 2000;356: 2013-2014.

13. Ciaraldi TP, Carter L, Seipke G, Mudaliar S, Henry RR. Effects of the long-acting insulin analog insu-lin glargine on cultured human skeletal muscle cells: Comparisons to insulin and IGF-I. J Clin Endocrinol Metab. 2001;86:5838-5847.

14. Bolli GB, Owens DR. Insulin glargine. Lancet. 2000;356: 443-445.

15. Ciaraldi TP, Sasaoka T. Review on the in vitro interaction of insulin glargine with the insulin/insulin-like growth fac-tor system: Potential implications for metabolic and mito-genic activities. Horm Metab Res. 2011;43:1-10.

16. Agin A, Jeandidier N, Gasser F, Grucker D, Sapin R. Glargine blood biotransformation: In vitro appraisal with human insulin immunoassay. Diabetes Metab. 2007;33: 205-212.

17. Kuerzel GU, Shukla U, Scholtz HE, et al. Biotransformation of insulin glargine after subcutaneous injection in healthy subjects. Curr Med Res Opin. 2003; 19:34-40.

18. Sommerfeld MR, Müller G, Tschank G, et al. In vitro metabolic and mitogenic signaling of insulin glargine and its metabolites. PLoS One. 2010;5:e9540.

19. Keller JM, Krohmer JS. Insulin transfer in the isolated human placenta. Obstet Gynecol. 1968;32:77-80.

20. Challier JC, Hauguel S, Desmaizieres V. Effect of insulin on glucose uptake and metabolism in the human placenta. J Clin Endocrinol Metab. 1986;62:803-807.

21. Boskovic R, Feig DS, Derewlany L, Knie B, Portnoi G, Koren G. Transfer of insulin lispro across the human pla-centa: In vitro perfusion studies. Diabetes Care. 2003;26: 1390-1394.

22. Pollex EK, Feig DS, Lubetsky A, Yip PM, Koren G. Insulin glargine safety in pregnancy: A transplacental trans-fer study. Diabetes Care. 2010;33:29-33.

23. Menon RK, Cohen RM, Sperling MA, Cutfield WS, Mimouni F, Khoury JC. Transplacental passage of insulin in pregnant women with insulin-dependent diabe-tes mellitus. Its role in fetal macrosomia. N Engl J Med. 1990;323:309-315.

24. Ludwig SM, Faiman C, Dean HJ. Insulin and insulin-receptor autoantibodies in children with newly diagnosed IDDM before insulin therapy. Diabetes. 1987;36:420-425.

25. Ottesen JL, Nilsson P, Jami J, et al. The potential immunogenicity of human insulin and insulin analogues evaluated in a transgenic mouse model. Diabetologia. 1994;37:1178-1185.

26. Sahin SB, Cetinkalp S, Ozgen AG, Saygili F, Yilmaz C. The importance of anti-insulin antibody in patients with type 1 diabetes mellitus treated with continuous subcuta-neous insulin infusion or multiple daily insulin injections therapy. Acta Diabetol. 2010;47:325-330.

27. Lantus [package insert]. Bridgewater, NJ: sanofi-aventis U.S.; 2009.

28. Hofmann T, Horstmann G, Stammberger I. Evaluation of the reproductive toxicity and embryotoxicity of insu-lin glargine (LANTUS) in rats and rabbits. Int J Toxicol. 2002;21:181-189.

29. Devlin JT, Hothersall L, Wilkis JL. Use of insulin glargine during pregnancy in a type 1 diabetic woman. Diabetes Care. 2002;25:1095-1096.

30. Holstein A, Plaschke A, Egberts EH. Use of insulin glargine during embryogenesis in a pregnant woman with type 1 diabetes. Diabet Med. 2003;20:779-780.

31. Dolci M, Mori M, Baccetti F. Use of glargine insulin before and during pregnancy in a woman with type 1 diabetes and Addison’s disease. Diabetes Care. 2005;28:2084-2085.

32. Di Cianni G, Volpe L, Lencioni C, et al. Use of insulin glargine during the first weeks of pregnancy in five type 1 diabetic women. Diabetes Care. 2005;28:982-983.

33. Woolderink JM, van Loon AJ, Storms F, de Heide L, Hoogenberg K. Use of insulin glargine during preg-nancy in seven type 1 diabetic women. Diabetes Care. 2005;28:2594-2595.

34. Graves DE, White JC, Kirk JK. The use of insulin glargine with gestational diabetes mellitus. Diabetes Care. 2006;29:471-472.

35. Kirss A. Use of glargine insulin before and during preg-nancy in Tartu University Women’s Clinic [abstract]. Diabet Med. 2006;23(Suppl 4):504. Abstract P1410.

36. Araujo C, Arrais Araujo C, Pitombo L, Lemos N. Use of insulin glargine during pregnancy in ten type 1 diabetic women. Abstract presented at: The Endocrine Society’s 88th Annual Meeting; June 24-27, 2006; Boston, MA. Abstract P2-853.

37. Caronna S, Cioni F, Dall’Aglio E, Arsenio L. Pregnancy and the long-acting insulin analogue: A case study. Acta Biomed 2006;77:24-26.

38. Ghosh D, Graham D, Street P, Elsheikh M. Use of insulin glargine during pregnancy in women with type 1 diabetes mellitus. Abstract presented at the 8th European Congress of Endocrinology; April 1-5, 2006; Glasgow, UK. Abstract P322.

39. Tahrani AA, Varughese GI, Wilkins JD, Taylor SE, Hanna FW. Glargine in pregnant patients with type 1 dia-betes. Diabet Med. 2008;25:111-112.

40. Torlone E, Gennarini A, Ricci NB, Bolli GB. Successful use of insulin glargine during entire pregnancy until deliv-ery in six type 1 diabetic women. Eur J Obstet Gynecol Reprod Biol. 2007;132:238-239.

41. Gallen IW, Jaap A, Roland JM, Chirayath HH. Survey of glargine use in 115 pregnant women with type 1 diabe-tes. Diabet Med. 2008;25:165-169.

42. Di Cianni G, Torlone E, Lencioni C, et al. Perinatal outcomes associated with the use of glargine during preg-nancy. Diabet Med. 2008;25:993-996.

43. Henderson CE, Machupalli S, Marcano-Vasquez H, Kerr P, Reilly KD. A retrospective review of glargine use in pregnancy. J Reprod Med. 2009;54:208-210.

44. Lepercq J, Jacqueminet S, Hieronimus S, Timsit J, Grimaldi A. Use of insulin glargine throughout preg-nancy in 102 women with type 1 diabetes. Diabetes Metab. 2010;36:209-212.

455

45. Casson IF, Clarke CA, Howard CV, et al. Outcomes of pregnancy in insulin dependent diabetic women: Results of a five year population cohort study. BMJ. 1997;315:275-278.

46. Penney GC, Mair G, Pearson DW; Scottish Diabetes in Pregnancy Group. Outcomes of pregnancies in women with type 1 diabetes in Scotland: A national population-based study. BJOG. 2003;110:315-318.

47. Jensen DM, Damm P, Moelsted-Pedersen L, et al. Outcomes in type 1 diabetic pregnancies: A nationwide, population-based study. Diabetes Care 2004;27:2819-2823.

48. Evers IM, de Valk HW, Visser GH. Risk of complications of pregnancy in women with type 1 diabetes: Nationwide prospective study in the Netherlands. BMJ. 2004;328:915.

49. Macintosh MC, Fleming KM, Bailey JA, et al. Perinatal mortality and congenital anomalies in babies of women with type 1 or type 2 diabetes in England, Wales, and Northern Ireland: Population based study. BMJ. 2006;333:177.

50. Lapolla A, Dalfrà MG, Di Cianni G, Bonomo M, Parretti E, Mello G; Scientific Committee of the GISOGD Group. A multicenter Italian study on pregnancy outcome in women with diabetes. Nutr Metab Cardiovasc Dis. 2008;18:291-297.

51. Meltzer SJ, Ryan EA, Feig DS, Thompson D, Snyder J. Preconception care for women with diabetes. Canadian Diabetes Association, clinical practice guidelines, 2003.

52. Feisullin K, Ness A, Baxter J. A cohort study of insulin glargine in diabetic pregnancies. Abstract presented at: the 27th Annual Meeting of the Society-of-Maternal-Fetal-Medicine. February 5 -10, 2007; San Francisco, CA. Am J Obstet Gynecol. 2007;195 (6 Suppl 1):S145. Abstract 465.

53. Hothersall LA, Caron E, Mullin K, Devlin JT. Insulin glargine versus NPH for managing diabetes in preg-nancy. Abstract presented at: the 66th Annual Meeting of the American Diabetes Association; June 9-13, 2006; Washington, DC. Diabetes. 2006;55(Suppl 1):A605. Abstract 2616-PO.

54. Pöyhönen-Alho M, Rönnemaa T, Saltevo J, Ekblad U, Kaaja RJ. Use of insulin glargine during pregnancy. Acta Obstet Gynecol Scand. 2007;29:1-4.

55. Price N, Bartlett C, Gillmer M. Use of insulin glargine during pregnancy: A case-control pilot study. BJOG. 2007; 114:453-457.

56. Imbergamo MP, Amato MC, Sciortino G, et al. Use of glargine in pregnant women with type 1 diabetes mellitus: A case-control study. Clin Ther. 2008;30:1476-1484.

57. Fang YM, MacKeen D, Egan JF, Zelop CM. Insulin glargine compared with neutral protamine Hagedorn insu-lin in the treatment of pregnant diabetics. J Matern Fetal Neonatal Med. 2009;22:249-253.

58. Egerman RS, Ramsey RD, Kao LW, et al. Perinatal outcomes in pregnancies managed with antenatal insulin glargine. Am J Perinatol. 2009;26:591-595.

59. Smith JG, Manuck TA, White J, Merrill DC. Insulin glargine versus neutral protamine Hagedorn insulin for treatment of diabetes in pregnancy. Am J Perinatol. 2009; 26:57-62.

60. Negrato CA, Rafacho A, Negrato G, et al. Glargine vs. NPH insulin therapy in pregnancies complicated by dia-betes: An observational cohort study. Diabetes Res Clin Pract. 2010;89:46-51.

61. Pantalone KM, Agarwal S, Faiman C. Glargine vs. NPH insulin therapy in pregnancies complicated by diabetes: An observational cohort study-comment on Negrato et al. Diabetes Res Clin Pract. 2011 Apr 18 [Epub ahead of print].

62. Pollex E, Moretti ME, Koren G, Feig DS. Safety of insu-lin glargine use in pregnancy: A systematic review and meta-analysis. Ann Pharmacother. 2011;45:9-16.

63. Koldovský O. Hormones in milk. Vitam Horm. 1995;50: 77-149.

64. Kulski JK, Hartmann PE. Milk insulin, GH and TSH: Relationship to changes in milk lactose, glucose and pro-tein during lactogenesis in women. Endocrinol Exp. 1983; 17:317-326.

65. Shehadeh N, Gelertner L, Blazer S, Perlman R, Solovachik L, Etzioni A. Importance of insulin content in infant diet: Suggestion for a new infant formula. Acta Paediatr. 2001;90:93-95.

66. Whitmore TJ, Trengove NJ, Hartmann PE. Insulin con-tent of human milk [abstract]. Breastfeed Med. 2008;3: 83-84.

67. Ratner RE, Hirsch IB, Neifing JL, Garg SK, Mecca TE, Wilson CA. Less hypoglycemia with insulin glargine in intensive insulin therapy for type 1 diabetes. U.S. study group of insulin glargine in type 1 diabetes. Diabetes Care. 2000;23:639-643.