Transplacental passage of insulin in pregnant women with insulin-dependent diabetes mellitus. Its role in fetal macrosomia

Efficacy, safety and lack of immunogenicity of insulin aspart compared with regular human insulin for women with gestational diabetes mellitus

AIM

The efficacy and safety of insulin aspart (IAsp), a rapid-acting human insulin analogue, were compared with regular human insulin (HI) as the bolus component of basal-bolus therapy for subjects with gestational diabetes mellitus (GDM).

METHODS

In a randomized, parallel-group, open-labelled trial, 27 women with GDM (age 30.7 +/- 6.3 years, HbA(1c) < 7%) were randomized to receive IAsp (5 min before meal) or HI (30 min before meal). The trial period extended from diagnosis of GDM (18-28 weeks) to 6 weeks postpartum.

RESULTS

Both treatment groups maintained good overall glycaemic control during the study (beginning and end of study HbA(1c)< or = 6%). During the meal test, mean glucose at week 6 (IAsp 4.2 +/- 0.57 mmol/l, HI 4.8 +/- 0.86 mmol/l) was slightly lower than at week 0 (IAsp 4.9 +/- 0.59 mmol/l, HI 5.1 +/- 0.36 mmol/l). However, change from baseline values for average glucose (IAsp -1.09 +/- 0.54 mmol/l, HI -0.54 +/- 0.74 mmol/l; P = 0.003) and C-peptide (IAsp -0.50 +/- 0.67 nmol/l, HI -0.30 +/- 0.70 nmol/l; P = 0.027) were significantly lower after IAsp treatment than HI treatment. No major hypoglycaemic events were reported during the study. Cross-reacting insulin antibody binding increased slightly from baseline in both treatments groups (end of study: IAsp 2.1 +/- 5.4%, HI 6.4 +/- 13.9%), whereas antibodies specific to IAsp or HI remained relatively low (< 1% binding).

CONCLUSION

IAsp was more effective than HI in decreasing postprandial glucose concentrations. Duration of IAsp injection 5 min before a meal rather than 30 min prior to meals offers a more convenient therapy for subjects with GDM. Overall safety and effectiveness of IAsp were comparable to HI in pregnant women with GDM.

Insulin analogues in the treatment of diabetes in pregnancy

This review reports the literature on the safety and efficacy of insulin analogues in pregnancy and thereby enables the clinician to choose the optimal insulin treatment protocol to achieve and maintain normoglycemia throughout pregnancies complicated by diabetes. This article also reviews the literature on the insulin analog during pregnancy and presents the authors' opinion as to the safety and efficacy of insulin analog treatment for the pregnant diabetic woman.

Metabolic imprinting: critical impact of the perinatal environment on the regulation of energy homeostasis

Epidemiological studies in humans suggest that maternal undernutrition, obesity and diabetes during gestation and lactation can all produce obesity in offspring. Animal models have allowed us to investigate the independent consequences of altering the pre- versus post-natal environments on a variety of metabolic, physiological and neuroendocrine functions as they effect the development in the offspring of obesity, diabetes, hypertension and hyperlipidemia (the 'metabolic syndrome'). During gestation, maternal malnutrition, obesity, type 1 and type 2 diabetes and psychological, immunological and pharmacological stressors can all promote offspring obesity. Normal post-natal nutrition can reduce the adverse impact of some of these pre-natal factors but maternal high-fat diets, diabetes and increased neonatal access to food all enhance the development of obesity and the metabolic syndrome in offspring. The outcome of these perturbations of the perinatal environmental is also highly dependent upon the genetic background of the individual. Those with an obesity-prone genotype are more likely to be affected by factors such as maternal obesity and high-fat diets than are obesity-resistant individuals. Many perinatal manipulations appear to promote offspring obesity by permanently altering the development of central neural pathways, which regulate food intake, energy expenditure and storage. Given their strong neurotrophic properties, either excess or an absence of insulin and leptin during the perinatal period are likely to be effectors of these developmental changes. Because obesity is associated with an increased morbidity and mortality and because of its resistance to treatment, prevention is likely to be the best strategy for stemming the tide of the obesity epidemic. Such prevention should begin in the perinatal period with the identification and avoidance of factors which produce permanent, adverse alterations in neural pathways which control energy homeostasis.

Safety and side effects of the insulin analogues

The analogue insulins were developed to more clearly mimic the basal and prandial components of insulin secretion for subjects with diabetes mellitus. Analogues are now widely used and have largely taken over from the conventional human recombinant insulins. It is important that these insulins are not only as effective as their predecessors, but are also safe and well-tolerated. In this manuscript, the authors review the adverse effects reported with analogue insulins and make a comparison with standard insulin treatments.

Insulin therapy in pregnancy complicated by diabetes: are insulin analogs a new tool?

It has been demonstrated that good metabolic control maintained throughout pregnancy can reduce maternal and fetal complications in diabetes. To achieve good metabolic control, before conception and throughout pregnancy, insulin therapy needs to be optimized, and, in this context, the new insulins currently on the market may help. We therefore review here what is known about the potential benefits and risks related to the use of these new insulins in pregnancy. Clinical and experimental data on insulin lispro strongly suggest that lispro does not have adverse maternal or fetal effects during pregnancy in women with preexisting diabetes, and also that its use in these women results in improved glycemic control, fewer hypoglycemic episodes, and improved patient satisfaction. In women with gestational diabetes mellitus (GDM), the use of insulin lispro is efficient in reducing postprandial hyperglycemia and some neonatal features related to hyperglycemia, thus stressing its usefulness in this condition. As for insulin aspart, clinical data on GDM patients shows the same efficacy as insulin lispro in lowering postprandial hyperglycemia, indicating that insulin aspart may be used in GDM when this condition is characterized by postprandial hyperglycemia. The results of a multicentric study now in progress on the efficacy and safety of insulin aspart in type 1 pregnant diabetic patients will definitely be useful in establishing whether this insulin is safe in pregnancy. For the moment, the use of insulin glargine during pregnancy is not recommended owing to the lack of data on maternal and fetal effects.

Obstetric complications due to autoantibodies

Autoimmune diseases are most common and most active in young women; it is therefore not uncommon for obstetricians and physicians to encounter pregnant women with these conditions, and knowledge of the potential maternal, foetal and neonatal complications is essential for good clinical management. The most common maternal autoimmune endocrine conditions in pregnancy are insulin-dependent diabetes mellitus and thyroid disease. Other relatively common non-endocrine autoimmune conditions include systemic lupus erythematosus and anti-phospholipid syndrome. Much rarer autoimmune conditions include autoimmune thrombocytopenia, rheumatoid arthritis, myasthenia gravis and Addison's disease. In this chapter, we discuss autoimmune endocrine conditions and briefly mention some non-endocrine conditions of particular importance.

Rationale for prevention and treatment of glucose-mediated macrosomia: a protocol for gestational diabetes

OBJECTIVE

To formulate a rationale for preventing and treating hyperglycemia during pregnancy and the concomitant risk of macrosomia.

METHODS

We reviewed pertinent studies in the literature and personal experience with patients who had gestational diabetes. In addition, dietary and exercise interventions in the management of such patients were assessed.

RESULTS

During pregnancy, sequential hormonal increases occur to provide glucose substrate to the fetus. When a pregnant woman has a limited insulin secretory capacity and cannot produce enough insulin to compensate for the effect of diabetogenic hormones, gestational diabetes occurs (usually during the second trimester). Maternal hyperglycemia reportedly increases fetal secretion of insulin, and fetal hyperinsulinemia may predispose the fetus to macrosomia. Thus, metabolic abnormalities associated with diabetes during pregnancy result in long-term effects on the offspring, including insulin resistance, obesity, and diabetes, which in turn may contribute to transmission of risk for development of the same problems in subsequent generations. Insulin therapy, dietary measures, and exercise have helped to achieve euglycemia in patients with gestational diabetes.

CONCLUSION

Universal screening for gestational diabetes is optimally performed at 26 weeks of gestation. Treatment of diagnosed cases, by insulin, diet, and exercise regimens, will decrease the occurrence of glucose-related macrosomia, improve the outcome of the pregnancy, and reduce the risks for obesity, hypertension, and diabetes in future progeny.

The safety and efficacy of insulin analogs in pregnancy

Diabetes during pregnancy is accompanied by increasing needs for maternal insulin and ongoing biological changes that cause maternal insulin requirements to reach higher and lower extremes throughout the day than in non-pregnant patients. As maternal hyperglycemia increases the risk of fetal and maternal morbidity, it is essential for the mother to maintain normoglycemia during pregnancy. With the advent of insulin analogs that feature improved absorption and physiological profiles over human insulin, the achievement of normoglycemia throughout pregnancy has become more attainable. This review provides a discussion of the application of the insulin analogs to diabetes during pregnancy and compares the benefits of rapid-acting insulin analogs with long-acting insulin analogs during pregnancy. This review further proposes a treatment protocol for achieving and maintaining normoglycemia throughout pregnancy.

Insulin sensitivity in the offspring of women with type 1 and type 2 diabetes

OBJECTIVE

To determine if insulin sensitivity is altered in prepubertal offspring exposed to a diabetic intrauterine environment.

RESEARCH DESIGN AND METHODS

Fifteen control children, 17 offspring of type 1 diabetic women, and 10 offspring of type 2 diabetic women, aged between 5 and 10 years, underwent a frequently sampled intravenous glucose tolerance test (FSIGTT). Weight and height were measured, and body composition was calculated using bioelectrical impedance. Bergman's minimal model was applied to the glucose and insulin measurements to obtain values for insulin sensitivity (Si), acute insulin response (AIR), and glucose effectiveness (Sg).

RESULTS

Si was lowest in the offspring of type 2 diabetic mothers, and AIR was highest in this group, although neither of these changes reached significance (Si, P = 0.2, and AIR, P = 0.3). Offspring of type 2 diabetic mothers had higher BMI SD scores (P = 0.004) and percentage fat mass (P = 0.002) than the children in the other two groups. The BMI SD score and percentage fat mass in the subjects, as well as maternal insulin dose, were negatively correlated with offspring insulin sensitivity.

CONCLUSIONS

Intrauterine exposure to hyperglycemia by itself was not associated with alterations in glucose regulation in prepubertal offspring. Children of mothers with type 2 diabetes, however, were overweight, and they had a tendency for a reduced Si. The combined effect of genetic and postnatal environmental factors, rather than prenatal exposure to hyperglycemia, may place this group at risk for developing impaired glucose tolerance in later life.

Gestational Diabetes:

Many clinicians in the United States routinely screen all pregnant women in their practices for gestational diabetes. Recently, the US Preventive Services Task Force re-emphasized that such screening is not supported by rigorous scientific evidence. Recommendations for diagnosis and management are based on an even scantier scientific foundation. Although this review questions several aspects of current dogma, it, too, is based on the frequently flawed existing data. It is surprising how, in spite of an abundance of published information on the subject, we continue to be ignorant of the real benefits of the widespread practice of screening and treating for gestational diabetes. The authors hope that the results of a randomized clinical trial, now in progress, will help to resolve some of the controversies surrounding gestational diabetes.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe the controversy surrounding the significance of gestational diabetes, to break down the data regarding the efficacy of screening for gestational diabetes, and to outline potential treatment options for gestational diabetes.

Adiponectin is present in cord blood but is unrelated to birth weight

OBJECTIVE

In adults, adiponectin is reduced in association with excess adiposity, type 2 diabetes, and hyperinsulinemia. We assessed whether adiponectin was 1) present in the fetal circulation, 2) altered in the fetal circulation in the presence of maternal diabetes, and 3) had relations to fetal cord blood insulin or adiposity.

RESEARCH DESIGN AND METHODS

We assessed adiponectin in cord blood in a large cohort of singleton offspring of diabetic mothers (ODM; n = 134) and control mothers (n = 45).

RESULTS

Adiponectin was present in cord blood and, in ODM, was higher in those delivered at later gestational ages (Spearman r = 0.18, P = 0.03). Adiponectin was slightly lower in ODM than control subjects (ODM 19.7 +/- 6.1 vs. control 21.8 +/- 5.3 micro g/ml; P = 0.04), although this difference could potentially reflect different gestational ages in the two groups (ODM 37.6 +/- 1.5 and control 40.1 +/- 1.1 weeks). In contrast to adults, adiponectin levels in the fetus were unrelated to the degree of adiposity, blood insulin, or leptin in either control subjects or ODM.

CONCLUSIONS

Adiponectin is present in cord blood but does not show expected physiological relations with adiposity as observed in adults.

The offspring of gestational diabetes

Gestational diabetes mellitus (GDM) usually develops in the second half of pregnancy and, in order to address the impact of GDM on the conceptus, several issues must be raised: what are the immediate implications for the fetus and the neonate and why do they happen? What are the consequences for the offspring? What can be done? In a theoretical model the whole pathogenesis and spectrum of fetal and neonatal mortality and morbidity could primarily be attributed to the excessive transferal of glucose from mother of fetus, inducing fetal hyperglycemia, leading to fetal pancreatic islet hypertrophy and beta-cell hyperplasia with a consequent rise in insulin secretion. However, besides, and in addition to glucose, it is quite possible that other metabolic fuels, from amino acids to lipids, may also cross the placenta further contributing to the adverse intrauterine environment. Depending upon the time of gestation during critical developmental stages, the same metabolic fuels would have different effects upon the fetus, the neonate and quite possibly, upon the long-term outcome from neurological and psychosocial impairment to the adult development of metabolic and cardiovascular disorders. Based on clinical and experimental evidence that poor maternal homeostasis is at the core of the problem, it is of paramount importance to identify women at risk of GDM and to keep a tight metabolic control in order to avoid immediate and long-term consequences for their offspring.

Maternal-fetal transport of hypoglycaemic drugs

Due to legal, ethical and monetary problems, drug studies in pregnancy are rare. Numerous pharmacokinetic and pharmacodynamic changes occur in pregnancy that can affect the efficacy and safety of drugs, and these are difficult to predict without appropriate studies. Drugs potentially useful and safe in pregnancy have to either not cross the placenta and/or be harmless to the fetus at clinically relevant concentrations. The first characteristic can be predicted using in vitro models such as the placenta perfusion model. In the case of glibenclamide (glyburide), in vitro experiments showed minimal maternal-fetal transfer, leading to completion of a successful clinical trial of this drug in gestational diabetes. Insulin, the main drug used in diabetes during pregnancy, has also been shown not to cross the placenta in vitro, as has insulin lispro. Animal insulin may cross the placenta when complexed with anti-insulin antibodies. Other sulphonylurea drugs (tolbutamide and chlorpropamide) have been shown to cross the placenta both in vitro and in vivo and to produce toxicity in the fetus. This review summarises the pharmacokinetic data available for hypoglycaemic drugs during pregnancy, as well as the potential role for the in vitro placenta perfusion model in the preclinical evaluation of drugs with potential usefulness in pregnancy.

Transfer of insulin lispro across the human placenta: in vitro perfusion studies

OBJECTIVE

Insulin lispro (Humalog), a human insulin analog, has a more rapid onset, earlier peak, and shorter duration of glucose lowering activity than regular human insulin. However, it is not known whether insulin lispro crosses the human placenta and reaches the fetus. Therefore, the objective of the present study was to examine whether insulin lispro crosses the placenta using the technique of perfusing a human placental lobule in vitro.

RESEARCH DESIGN AND METHODS

Term human placentae from uncomplicated pregnancies were obtained immediately after delivery. Insulin lispro, at concentrations ranging from 100 to 1000 micro U/ml, was introduced into the maternal reservoir. The maternal side of the placenta was perfused with constant concentration of lispro insulin; the fetal circulation was closed. Samples were drawn from both the maternal and fetal circulations at regular intervals. The appearance of insulin lispro in the fetal circulation was analyzed by a specific radioimmunoassay.

RESULTS

No placental transfer of lispro could be detected during perfusion with 100 and 200 micro U/ml. In contrast, there was a small concentration-dependent transfer to the fetus at concentrations of 580 micro U/ml and higher, detectable after at least an hour of constant concentration of insulin lispro during perfusion. The rate of placental transfer was 0.019 micro U x min(-1) x g tissue(-1) at maternal levels of 580 micro U/ml and 0.045 micro U x min(-1) x g(-1) tissue at maternal levels of 1000 micro U/ml. Measuring lispro levels in 11 pregnant women revealed that a dose of 50 units may achieve serum concentrations >200 micro U/ml with apparent linear correlation between dose and levels.

CONCLUSIONS

Insulin lispro is not likely to cross the placenta at a single standard dose. This study suggests that insulin lispro is unlikely to reach or harm the unborn baby.

Pregnancy outcome in Type 1 diabetes mellitus treated with insulin lispro (Humalog)

AIMS

The use of insulin lispro in pregnancy has not been systematically investigated despite its increasing use. Pooled data from seven centres with experience in the use of insulin lispro were accumulated to evaluate pregnancy outcome in women with Type 1 diabetes.

METHODS

Seven units with specialist obstetric diabetes services were recruited to describe their total experience with insulin lispro in pregnancy. Outcomes with respect to the rate of miscarriage, congenital abnormality, perinatal mortality and maternal parameters were recorded in a standardized format.

RESULTS

Outcomes on 71 babies from 76 pregnancies were documented. There were six (7.8%) early miscarriages. All 71 babies were liveborn with a mean gestational age of 37.2 weeks, and median birthweight of 3230 g. Seven babies weighed > 4 kg. There were four congenital abnormalities (5.6%). There was a 72% increase in the mean insulin dose (0.75-1.29 IU/kg per day). Maternal glycaemic control improved throughout pregnancy. No women developed retinopathy de novo during pregnancy and six with established retinopathy required laser therapy during pregnancy.

CONCLUSIONS

The use of insulin lispro in Type 1 diabetes during pregnancy results in outcomes comparable to other large studies of diabetic pregnancy.

The utility and efficacy of the new insulins in the management of diabetes and pregnancy

The quest for tight glucose control has led to the development of insulin analogues (insulin lispro, insulin aspart, insulin glargine) designed to optimize glucose control while minimizing the impact of insulin therapy on daily life. Women with diabetes are increasingly likely to become pregnant on these new products and to benefit from their use while pregnant. Caution over the use of new medications in pregnancy has limited experience, but increasing evidence is emerging that use of insulin lispro is not associated with excess risk of fetal malformations, is associated with similar or better outcomes during pregnancy, and is preferred over regular insulin. Similar evidence for the other insulin analogues has yet to emerge, but is unlikely to be dissimilar.

Oral hypoglycemic agents and the pregnant diabetic: "from bench to bedside"

Today, the criteria for diagnosis and treatment have evolved into an evidence-based medicine approach. The need for evidence-based information is especially critical in the management of gestational diabetes, in general, and especially in the use of oral hypoglycemic agents. These agents have been categorically contraindicated for decades in the United States based on anecdotal and/or weak evidence for these recommendations. In this article, the similarities between gestational and type 2 diabetes are described and the rationale for the use of oral hypoglycemic agents for the treatment of both are discussed. The author will show how research from basic sciences (placental transfers) to clinical studies (perinatal outcome) can lead to significant evidence on which to base management recommendations.

Antigen-specific responses in autoimmunity and tolerance

Autoantibodies to the hormone insulin arise spontaneously in the insulin autoimmune syndrome and in the prodrome of type I diabetes. Further, administration of insulin to individuals without autoimmune disease routinely results in antibodies that bind autologous hormone. These observations suggest that physiological levels of hormones, such as insulin, are below critical thresholds for signaling tolerance induction, a state termed clonal ignorance. In contrast, studies from our laboratory on the genetic origins and structure of V genes used by insulin antibodies suggest that the anti-insulin repertoire is tightly regulated. We have shown that B cells in mice harboring an insulin antibody transgene are functionally silenced. These findings verify that tolerance is active for small molecules, even when they are present at low concentrations. Despite active tolerance, insulin antibodies are sustained in the repertoire of normal animals by several mechanisms, including activation by TI antigen signals, unique display of conformational epitopes, and the recruitment of B cells previously selected by responses to other antigens. This essay reviews our current understanding of escape pathways for anti-insulin B cells.

Fetal hyperinsulinemia increases farnesylation of p21 Ras in fetal tissues

Even though the role of fetal hyperinsulinemia in the pathogenesis of fetal macrosomia in patients with overt diabetes and gestational diabetes mellitus seems plausible, the molecular mechanisms of action of hyperinsulinemia remain largely enigmatic. Recent indications that hyperinsulinemia "primes" various tissues to the mitogenic influence of growth factors by increasing the pool of prenylated Ras proteins prompted us to investigate the effect of fetal hyperinsulinemia on the activitiy of farnesyltransferase (FTase) and the amounts of farnesylated p21 Ras in fetal tissues in the ovine experimental model. Induction of fetal hyperinsulinemia by direct infusion of insulin into the fetus and by either fetal or maternal infusions of glucose resulted in significant increases in the activity of FTase and the amounts of farnesylated p21 Ras in fetal liver, skeletal muscle, fat, and white blood cells. An additional infusion of somatostatin into hyperglycemic fetuses blocked fetal hyperinsulinemia and completely prevented these increases, specifying insulin as the causative factor. We conclude that the ability of fetal hyperinsulinemia to increase the size of the pool of farnesylated p21 Ras may prime fetal tissues to the action of other growth factors and thereby constitute one mechanism by which fetal hyperinsulinemia could induce macrosomia in diabetic pregnancies.

Amniotic fluid insulin at 14-20 weeks' gestation: association with later maternal glucose intolerance and birth macrosomia

OBJECTIVE

To examine the hypothesis that early second trimester amniotic fluid (AF) insulin concentration is elevated and later fetal growth is augmented in gravidas demonstrating later oral glucose intolerance.

RESEARCH DESIGN AND METHODS

In this prospective observational cohort study, AF was sampled at 14-20 weeks' gestation in 247 subjects, and 1-h 50-g oral glucose challenge tests (GCTs) were performed at > or = 24 weeks. AF insulin was assayed by an automated immuno-chemiluminometric assay (8). Macrosomia was defined as birth weight above the 90th centile.

RESULTS

AF insulin concentration (range 1.4-44.5 pmol/l) correlated positively with gestational age and maternal weight. A logistic regression analysis, adjusted for maternal age and midpregnancy weight, showed increased AF insulin multiples of gestational age-specific medians to be associated with subsequently diagnosed gestational diabetes mellitus (GDM) (OR 1.9, CI 1.3-2.4, P = 0.029). Among 60 subjects with GCT values > 7.2 mmol/l, each unit increase in AF insulin multiple of median (MOM) was associated with a threefold increase in fetal macrosomia incidence (3.1, 1.3-4.9, P = 0.048).

CONCLUSIONS

An elevated AF insulin concentration at 14-20 weeks' gestation is associated with subsequently documented maternal glucose intolerance. Among gravidas with GCT values > 7.2 mmol/l, elevated early AF insulin concentration is associated with fetal macrosomia. Maternal glucose intolerance may affect fetal insulin production before 20 weeks' gestation.

Techniques to study human placental transport

Pregnancy in the 20th century involves women of many age groups from early teens to the fourth or fifth decade. Modern medicine and in vitro fertilization techniques have increased options for pregnancy and childbirth. Pregnancy is a dynamic state, and medical concerns may involve disorders of the fetus and mother requiring medications and special nutrients. Therefore, different techniques have been developed to evaluate the placental transfer of drugs and nutrients using tissues and cells derived from human placenta. These include (a) isolated tissues and cells to study placental transport, (b) primary and malignant trophoblast cell cultures and (c) biophysical methods for studying placental transport. Also, convenient study models have been developed to evaluate placental transfer of safe drugs in pregnant women. Some of the drugs studied by these techniques and models include (a) anesthetics and pain medications used during delivery, (b) antibiotics and anti-bacterials used to cure infections, (c) drugs abused by pregnant women and (d) nutrients required for proper fetal growth. Placental transfer and exchange mechanisms are complicated processes, and in vitro models reflect only partially the equilibria that exist among mother, placenta and fetus. The perfused cotyledon model is elegant and simple but gives only restricted information. Isolated placental tissues give useful information about the pharmacological effects of drugs. Metabolic studies using human placental models provide information on the metabolism of a drug during placental transfer and accumulation of the drug or its metabolite in the placenta or fetal circulation. Several studies on the transplacental passage of drugs exist but many questions regarding the transfer of drugs between the maternal and fetal circulations and clearance of drugs from fetal circulation have yet to be answered. This article reviews in vitro and in vivo methods for evaluation of transplacental transport of drugs and their current effectiveness to obtain clinically useful data.

Anti-insulin antibodies and birth weight in pregnancies complicated by diabetes

Free insulin cannot cross the placenta but insulin complexed to anti-insulin antibodies has been demonstrated in cord blood. We studied whether antibody-bound insulin in diabetic patients can evoke fetal macrosomia independently of maternal metabolic control. In 457 non insulin-treated controls and 173 insulin-treated diabetic patients we measured 1187 anti-insulin antibody levels and maternal blood glucose, maternal fructosamine, cord blood insulin, cord blood C-peptide, cord blood fructosamine and amniotic fluid insulin. Mean anti-insulin antibody levels in maternal blood and cord blood were significantly higher in insulin treated diabetic patients (4.6 and 5.4 U/ml) than in controls (1.8 and 1.7 U/ml) with maxima of 89.2 in maternal and 120.0 U/ml in cord blood, respectively. In insulin treated diabetic patients 16.6% (maternal blood) and 22% (cord blood) anti-insulin antibody levels were above the 97th percentile. There was a high significant correlation between maternal and cord blood anti-insulin antibodies (R = 0.987, P = < 0.0001), but no correlation of anti-insulin antibodies with maternal (glucose, fructosamine) or fetal (insulin, C-peptide, and fructosamine in cord blood, amniotic fluid insulin) metabolic parameters. While maternal and fetal metabolic parameters correlated with birth weight neither maternal nor cord blood anti-insulin antibody levels correlated with birth weight. These findings do not support the hypothesis that maternal anti-insulin antibodies independently influence fetal weight.

Transport of proteins across the human placenta

PROBLEM

The transport of various proteins across the human placenta was investigated by comparing maternal and fetal concentrations of tetanus antigen (TT-AG), anti-tetanus (TT)-immunoglobulin G (IgG) (following maternal vaccination), IgA, human chorionic gonadotropin (hCG), human placental lactogen (hPL), and alpha-fetoprotein (AFP) at term.

METHOD OF STUDY

The concentrations of the six proteins were determined using enzyme-linked immunosorbent assay in serum of maternal venous and umbilical (fetal) vein samples obtained at delivery from uncomplicated term pregnancies (n = 16).

RESULTS

The ratios (mean +/- standard deviation) of fetal (umbilical) to maternal level were 1.41 +/- 0.33 (anti-TT-IgG), 0.91 +/- 0.37 (TT-AG), 0.002 +/- 0.001 (IgA), 0.003 +/- 0.001 (hCG), and 0.008 +/- 0.004 (hPL), while the maternal:fetal concentration ratio of AFP was 0.002 +/- 0.002. IgA, hCG, hPL, and AFP showed a close correlation between maternal and fetal levels varying between r2 = 0.47 to 0.73 (P < 0.004-0.0001). Because AFP is produced by the fetus while IgA originates in the mother, the appearance of small amounts of these two proteins in the maternal or fetal compartment, respectively, suggests a slow rate of diffusion following a high concentration gradient. The detection of hCG and hPL in fetal serum is also interpreted as diffusion from the maternal into the fetal blood. Anti-TT-IgG has a significantly higher concentration in the fetal as compared with the maternal serum, which is in line with the well-documented active transfer of IgG. Fetal TT-antigen levels were similar to maternal concentrations, showing a close correlation (r2 = 0.74, P < 0.0001) between the two proteins.

CONCLUSIONS

The correlation between maternal and fetal concentrations of various proteins like IgA (150,000 Da), hCG (42,000 Da), and hPL (21,000 Da) suggests passive diffusion of these macromolecules across the placenta from the maternal to the fetal side, albeit at a slow rate. A similar process is postulated for AFP (70,000 Da) diffusing in the opposite direction from the fetus to the mother. There was no significant difference between the transplacental fetomaternal gradient of IgA and hCG and the maternal-fetal gradient of AFP. In view of the substantially larger volume of circulating maternal as compared with fetal blood, a significantly higher rate of crossing of AFP as compared with the other proteins must be assumed. It is uncertain whether a difference in the rate of transplacental transfer in the two directions or an additional source of AFP production in the maternal compartment explains the high maternal level. Anti-TT-IgG concentration is significantly higher in fetal than in maternal serum suggesting active transfer from the mother to the fetus. Furthermore, there is considerable transfer of TT-AG and a close correlation of fetal:maternal ratios of anti-TT-IgG (150,000 Da) and TT-AG (150,000 Da) could be an indication for a specific transfer of the antigen antibody complex.

Pregnancy does not induce or worsen retinal and peripheral nerve dysfunction in insulin-dependent diabetic women

In order to verify whether pregnancy induces or worsens diabetic retinopathy or somatic and autonomic neuropathy, 16 insulin-dependent diabetic (IDDM) pregnant women, 14 age-matched nondiabetic pregnant women, and 12 IDDM nonpregnant women matched for age and disease duration were studied. Plasma glucose, HbA1c, and fructosamine were repeatedly assayed during pregnancy. Retinopathic and neuropathic endpoints were evaluated through ophthalmoscopy, electrophysiology of left peroneal and sural nerves (motor and sensory conduction velocities), and cardiovascular autonomic tests (deep breathing, cough test, lying-to-standing). In the IDDM pregnant women, evaluations were performed three times during pregnancy and 6 months after delivery. Good metabolic control was achieved during pregnancy. At baseline, nine IDDM pregnant women did not show signs of retinopathy, and seven had nonproliferative retinopathy. Only one patient showed worsening during pregnancy, but she improved after delivery. Motor conduction velocity, significantly lower in IDDM pregnant women, progressively improved, and, in the third trimester, was not significantly different from that of nondiabetic pregnant women. At baseline, none of the IDDM pregnant women had abnormal responses to cardiovascular autonomic tests. During pregnancy, the response to deep breathing appeared temporarily reduced in all pregnant women, possibly due to lowered ventilatory excursion at the end of pregnancy. In IDDM women with minimal or no retinopathy, and subclinical or no peripheral neuropathy, pregnancy does not appear to induce or worsen these complications.

Diabetes during pregnancy does not alter whole body bone mineral content in infants

A previous study using single photon absorptiometry has reported low bone mineral density of the radius in infants of diabetic mothers. The aim of this study was to assess by dual x-ray absorptiometry the whole body bone mineral content (WbBMC) and the body composition of 40 infants of diabetic mothers at birth (mean gestational age +/- SD, 37.5 +/- 1.3 weeks; mean birth weight +/- SD, 3815 +/- 641 g). WbBMC was not correlated with gestational age, but was well correlated with birth weight (r = 0.73; P = 0.0001) and also with fat mass (r = 0.87; P = 0.0001) and lean mass (r = 0.42; P = 0.008). The z-scores +/- SD adjusted for weight for WbBMC and fat mass were significantly increased (1.3 +/- 0.9 and 2.6 +/- 1.3, respectively (P < 0.0001), but were not significantly influenced either by in utero growth or by the type of the diabetes mellitus of the mother. Bone mineralization and fat mass studied by whole body dual x-ray absorptiometry are increased at birth in these infants compared with reference curves.

Protein transport across the in vitro perfused human placenta

PROBLEM

Placental transport of various proteins present in human serum, such as immunoglobulins (IgG, IgA), specific anti-tetanus IgG (anti-TT-IgG), and tetanus toxoid-antigen (TT-AG), was investigated. In addition, the transport of IgG modified with biotin (IgG-BT) and 14C-bovine serum albumin (14C-BSA, a permeability marker for macromolecules), was assessed.

METHOD OF STUDY

During the perfusion of an isolated cotyledon from human term placenta the perfusate was recirculated on both maternal and fetal sides. After an initial stabilisation phase of 2 hr (control phase), media on both sides were exchanged and perfusion was continued comparing two different conditions (experimental phase). In the first group (control experiments [A, n = 3]), no test proteins were added during the experimental phase (4-6 hr). In the second group (B, n = 5), during the experimental phase (6 hr) the maternal perfusion medium contained IgG (Sandoglobuline, 6-10 g/L), anti-TT-IgG (21-25 mg/L), TT-AG (0.19-0.24 mg/L), and IgA (0.13-0.19 g/L). IgG-BT (2 g/L) and 14C-BSA (30-40 nCi/ml) were added to the medium on the maternal side. IgGs and TT-AG were determined by specific enzyme-linked immunosorbent assay.

RESULTS

Both groups showed stable metabolic conditions with constant rates of glucose consumption, lactate production, and hormone (human chorionic gonadotropin, human placental lactogen) release observed throughout the experiment. Washout levels of endogenous IgG and IgA observed in the maternal circuit at the end of the control period were 5 and 1000 times higher than in the fetal circuit. In the experimental phase these levels remained constant at 50-80% of control levels with no change in the last 4 hr of perfusion (group A). In group B, with addition of extra proteins, trace amounts of IgG-BT, IgA, and 14C-BSA were detectable in the fetal circuit within 1 hr, with no significant further increase in circulating levels in the following 4 hr of the perfusion. In contrast, the detection of IgGs in the fetal circuit was delayed by 2 hr; thereafter, a continuous linear increase was observed for all IgGs. TT-AG in fetal perfusate was below the detection limit. TT-AG was found on the fetal side only after ultrafiltration of samples obtained at the end of the experiment. For permeability comparison, the ratio between concentrations on the fetal and maternal side multiplied by 100 ([F:M] x 100), as detected after 6 hr of perfusion, was assessed (n = 5, mean +/- SD). Labelling of IgG with biotin (IgG-BT) reduced its placental transfer by a factor 10 (0.04 +/- 0.01) when compared with the natural IgG (0.49 +/- 0.08) or the specific antibody (anti-TT-IgG). The relative fetal-to-maternal ratio found for TT-AG (0.48 +/- 0.12) was similar to anti-TT-IgG (0.46 +/- 0.11), and approximately 4 and 50 times that of 14C-BSA (0.12 +/- 0.03) and IgA (0.01 +/- 0.01), respectively. Considering that the molecular weights of TT-AG and anti-TT-IgG were at least twice that of BSA and similar to IgA, the difference in transfer suggests a specific mechanism of transport.

CONCLUSIONS

Compared with other proteins there is a significantly increased transfer of IgGs across the in vitro perfused human placenta from the maternal to the fetal side, indicating a specific transport mechanism. The similarity in transfer of anti-TT-IgG and tetanus antigen may suggest the transport as antibody-antigen complex.

Location of insulin receptors in the placenta and its progenitor tissues

The insulin receptor gene is constitutively expressed, so the presence of insulin receptor proteins might be expected on all mammalian tissues, with the plasma membrane as the predominant site of receptor location. Results reviewed here indicate that insulin receptors are also present in all placental tissues and the placenta's progenitor tissues and cells, i.e., oocytes, spermatozoa, and preimplantation embryos, in most of the species studied. Receptor densities, however, vary among individual cells and cell types and at various developmental stages. Three aspects deserve emphasis. 1) In human placenta, the insulin receptor distribution pattern is characterized by a spatiotemporal change between first trimester and term. At the beginning of pregnancy, insulin receptors are found predominantly on the maternal side (apical membrane of syncytiotrophoblast, low density on cytotrophoblast); at term, however, they are on the fetal side (lining the fetal vessels). This suggests that, in the first trimester, maternal insulin regulates insulin-dependent processes, whereas, at term, it must be fetal insulin mainly controlling these processes. 2) The majority of insulin receptors is expressed on structures that are currently assumed to drive placental growth, i.e., syncytial sprouts and mesenchymal villi in first-trimester placentas and fetal endothelium at term. Therefore, we hypothesize a growth-promoting function, among others, of insulin on the placenta. 3) At present, no histologic evidence is available to demonstrate insulin receptors in structures commonly associated with receptor-mediated endocytosis. Whether placental insulin receptors are internalized, therefore, awaits clarification.

Oxidative metabolism in insulin-treated gestational diabetes mellitus

To investigate whether protein, carbohydrate, and fat metabolism was normalized in insulin-treated gestational diabetes mellitus (GDM), eight Hispanic women with GDM and eight healthy controls were studied at 32-36 wk of gestation and 6 wk postpartum. Net substrate utilization was measured using room respiration calorimetry. Exogenous substrate oxidation was determined by 13C recovered in breath CO2 from 13C-labeled leucine, glucose, and Hiolein. Women with GDM had higher 24-h oxygen consumption, carbon dioxide production, total energy expenditure, and basal metabolic rates than controls due to larger body mass. Adjusted for weight or fat-free mass, total energy expenditure, basal metabolic rate, and basal and 24-h whole body net protein, carbohydrate, and fat utilization did not differ between insulin-treated GDM subjects and controls in pregnancy or postpartum. Oxidation of [13C]leucine and [13C]glucose did not differ by group or pregnancy status. Recovery of exogenously administered [13C]Hiolein, a biosynthetic triglyceride, as breath 13CO2 was significantly lower in the GDM group antepartum and postpartum (P = 0.02), indicating lower oxidation of exogenous triglycerides in GDM.

Short- and long-range complications in offspring of diabetic mothers

The perinatal mortality rate of infants of diabetic mothers (IDMs) has declined dramatically from 250 per 1000 live births in the 1960s to a near-normal 20 per 1000 live births in the 1980s. Five to 8% of all IDMs suffer from major congenital malformations, and it is the latter that are responsible for 50% of these perinatal deaths. It has been shown that tight glycemic control prior to conception and during pregnancy can prevent an excess rate of congenital malformations, fetal macrosomia, birth trauma, and neonatal respiratory distress syndrome. We briefly review the short- and long-range complications that occur in offspring of diabetic mothers (ODMs) from gestation through young adulthood. Short-term neonatal complications, such as hypoglycemia, hypocalcemia, hypomagnesemia, hyperbilirubinemia, and polycythemia, are related mainly to fetal hyperinsulinemia, hypoxemia, and prematurity. They are readily controllable within the setup of modern neonatal intensive care units. Long-range complications include an increased rate of childhood and adolescent obesity, impaired glucose tolerance or diabetes mellitus, and subtle neuropsychological dysfunctions. These may be related to the severity of the maternal hyperglycemia during pregnancy, the consequent fetal hyperinsulinemia, and third trimester maternal lipid metabolism disturbances. Today we have at hand the knowledge and tools to properly treat both pregestational and gestational diabetes. Increased education of the general practitioner and the target population regarding early referral of pregestational diabetic mothers and the implementation of screening programs for gestational diabetes will further reduce diabetic pregnancy-related morbidity.

Fetal size at birth in relation to quality of blood glucose control in pregnancies complicated by pregestational diabetes mellitus

OBJECTIVE

To determine the relation between maternal levels of blood glucose and glycated haemoglobin (HbA1c) and infant size at birth in pregestational diabetes.

DESIGN

Longitudinal study from 6 to 14 weeks gestation. Women were treated intensively with insulin, aiming at normoglycaemia but avoiding hypoglycaemia. Blood glucose was determined six times daily, HbA1c every four weeks. Individual mean fasting and postprandial glucose levels were calculated for three-week periods of gestation. Birthweight > 2 SD or within +/- 2 SD for gestational age and gender was classified as large (LGA) or appropriate (AGA), respectively. Birthweight ratio was calculated as the ratio of birthweight to normal mean birthweight after correction for gestational age and gender.

PARTICIPANTS

One hundred and thirteen consecutive pregnant women with pregestational diabetes and their newborn infants.

RESULTS

Perinatal mortality was nil, the rates of spontaneous preterm delivery (8.9%) and severe maternal hypoglycaemia (4.4%) were low. Mothers with LGA infants (26%) had a significantly higher fasting glucose between weeks 27 and 32 than mothers of AGA infants (P < 0.01). Relative birthweight was significantly and independently associated with pre-pregnancy bodyweight (r = 0.24, P < 0.05) and fasting glucose at weeks 27 to 29 (r = 0.27, P < 0.01) but together could only explain 12.3% of the variation in birthweight (mult. r = 0.35, P < 0.01). HbA1c correlated with glucose levels but was unrelated to birthweight ratio. The fasting glucose level between weeks 30 and 32 was significantly interrelated with the fasting glucose level from each of the six preceding three-week periods.

CONCLUSION

Near normoglycaemia cannot be obtained in all patients, presumably due to intrinsic differences in glucoregulatory ability between individuals. The incidence of LGA infants was unexpectedly high. The modest abnormality in glycaemic control in mothers with LGA infants could only partly explain fetal oversize, suggesting that other factors must be implicated to explain fetal growth acceleration.

Common clinical manifestations of maternal diabetes in newborn infants: implications for the practicing pediatrician

Even though perinatal mortality of infants of diabetic mothers has decreased remarkably in recent years and now approaches that of the general population, these infants still face a multitude of potential complications and the propensity for increased morbidity, both in utero and postnatally. Many of these complications are clearly related to the metabolic status of the diabetic mother. Increasing awareness among insulin-dependent diabetic patients and health providers of the need for glycemic control and the ever-growing understanding of the peculiarities of diabetic pregnancies eventually should combine to provide the best possible outcome for these infants.

Changes in surfactant protein A mRNA levels in a rat model of insulin-treated diabetic pregnancy

Maternal diabetes during pregnancy is associated with increased risk of neonatal respiratory distress syndrome (RDS). Previous studies using rat models for the diabetic pregnancy have documented decreased amounts of surfactant protein mRNA in the lungs of fetuses. In this study, we measured fetal lung surfactant-associated protein A (SP-A) mRNA from diabetic rats treated with insulin by daily injection or osmotic pump. Lungs were taken from fetuses on gestational d 20, and RNA was isolated and subjected to Northern blotting and densitometry to quantify SP-A mRNA. Fetal lung SP-A mRNA from untreated diabetic pregnancies was 34 +/- 2.9% of control. Insulin treatment increased levels to 55 +/- 4.2% of control values. Fetal lung SP-A mRNA levels were affected by the timing, length, and effectiveness of insulin treatment. Although levels from all treatment groups were still less than control values, insulin treatment during the last 5 or 10 d of pregnancy resulted in a substantial increase in SP-A mRNA levels over those of from untreated diabetic pregnancies. However, fetuses from the group with insulin treatment for the entire pregnancy showed decreases in fetal SP-A mRNA levels. Although the mechanism(s) responsible for the effects of diabetes and its treatment on fetal SP-A expression remain unclear, it appears unlikely that hyperglycemia is the principal cause.

Naturally occurring insulin autoantibodies in neonates of normal pregnancies and their relationship to insulinemia and birth weight

OBJECTIVE

The objectives of this study were to determine whether insulin autoantibodies are present in umbilical cord blood from normal pregnancies, determine whether cord blood insulin autoantibody levels correlate with respective maternal levels at delivery, determine whether cord blood insulin autoantibody levels are related to cord blood or maternal insulin levels, and to determine what relationship neonatal birth weight has with either cord blood insulin autoantibody and insulin levels or maternal insulin autoantibody and insulin levels.

STUDY DESIGN

Paired umbilical cord and maternal serum samples were taken from 70 normal subjects at delivery. Measurements of serum insulin autoantibody (competitive charcoal radiobinding assay) and insulin (radioimmune inhibition assay) levels were performed. Multiple linear regression analysis and paired t tests were used for data analyses.

RESULTS

Neonatal insulin autoantibody levels (120 nU/ml) were more than two times higher than maternal levels (49 nU/ml) (p < 0.001). No correlation was observed between neonatal and maternal insulin autoantibody levels (r = 0.14, p = 0.25). A positive correlation of both neonatal and maternal insulin with birth weight was observed (r = 0.28, p < 0.02; and r = 0.36, p < 0.01, respectively).

CONCLUSIONS

These results suggest that the insulin autoantibody levels in fetal cord blood are not related to maternal levels in normal uncomplicated pregnancies. In addition, insulin levels in both maternal and neonatal circulations were positively correlated with increased birth weight in the normal pregnancies studied.

Comparative placental transport of oral hypoglycemic agents in humans: a model of human placental drug transfer

OBJECTIVE

This study compares the human placental transport of glyburide, glipizide, chlorpropamide, and tolbutamide.

STUDY DESIGN

The recirculating single cotyledon human placenta model tested maternal-to-fetal transport in term placentas perfused immediately after delivery. Drug levels were measured by high-performance liquid chromatography and liquid scintillation spectrometry, and transport rates were calculated by comparing maternal and fetal concentrations.

RESULTS

The transport of these substances differed significantly over a tenfold range (analysis of variance, p < 0.0008). A significant association exists by multiple linear regression between drug transfer and molecular weight, dissociation constant, and the octanol-water partition coefficient (R2 = 0.91, p < 0.0001).

CONCLUSIONS

There is significant variability in human placental transfer rates of the oral hypoglycemics, which strongly correlates with molecular properties. These data suggest that less fetal exposure may occur with second-generation sulfonylureas and anticipate that regression models may be useful in selecting agents that minimize placental transport to the fetus.

Rigorous management of insulin-dependent diabetes mellitus during pregnancy

The effect of rigorous management of insulin-dependent diabetes mellitus (IDDM) during pregnancy on the perinatal outcome was assessed by comparing 78 prepartum gravid patients with IDDM managed prospectively with 78 matched controls. The diabetic women were treated with insulin by either infusion pump or split-dose therapy, with the goal of normalization of the fasting blood sugars and hemoglobin Hb A1c values. Differences in the perinatal outcome were evaluated by either chi-square or analysis of variance. Of the women with IDDM, 14% where White class B, 43% class C, 26% class D, 17% classes R and F. The mean Hb A1c value in the first half of pregnancy was 8.49% +/- 2.30%, and 7.34% +/- 1.79% in the second half. Women with IDDM had higher rates of premature delivery (31% vs. 10%, P = 0.003), pre-eclampsia (15% vs. 5%, P = 0.035), and cesarean section (55% vs. 27%, P = 0.002). Complications of infants born to diabetic mothers included large size for gestational age (41% vs. 16%, P = 0.0002), hypoglycemia (14% vs. 1%, P = 0.0025), hyperbilirubinemia (46% vs. 23%, P = 0.0002), and respiratory distress (12% vs. 1%, P = 0.008). The Apgar scores and mortality were similar. Congenital malformations occurred in 7.7% of infants of diabetic mothers and 1.3% of controls (P = 0.05). The maternal Hb A1c level did not correlate with the infant size for gestation. Although the improved medical management of IDDM has decreased neonatal mortality, significant perinatal complications persist.

Carbon source induces growth of stationary phase yeast cells, independent of carbon source metabolism

Nutrients regulate the proliferation of many eukaryotic cells: in the absence of sufficient nutrients vegetatively growing cells will enter stationary (G0 like) phase; in the presence of sufficient nutrients non-proliferative cells will begin growth. Previously we have shown that glucose is the critical nutrient which stimulates a variety of growth-related events in the yeast Saccharomyces cerevisiae (Granot and Snyder, 1991). This paper describes six new aspects of the induction of cell growth events by nutrients in S. cerevisiae. First, all carbon sources tested, both fermentable and non-fermentable, induce growth-related events in stationary phase cells, suggesting that the carbon source is the critical nutrient which stimulates growth. Second, the continuous presence of glucose is not necessary for the induction of growth events, but rather a short 'pulse' of glucose followed by an incubation period in water will induce growth events. Third, growth stimulation by glucose occurs in the absence of the SNF3 high affinity glucose transporter. Fourth, growth stimulation occurs independent of carbon source phosphorylation and carbon source metabolism. Fifth, growth induction by carbon source does not require protein synthesis or extracellular calcium. Sixth, following stimulation by carbon source, the cells remain induced for more than 2 h after removal of the carbon source. We suggest a general model in which different carbon sources act as signals to induce the earliest growth events during or following its entry into the cell and that these growth events do not depend upon metabolism of the carbon source.

Randomized trial of human versus animal species insulin in diabetic pregnant women: improved glycemic control, not fewer antibodies to insulin, influences birth weight

OBJECTIVE

Macrosomia occurs in infants of diabetic mothers in spite of "nearly normal maternal blood glucose levels" with insulin treatment. Insulin antibodies may carry bound insulin into the fetal blood and thus may be associated with fetal hyperinsulinemia and macrosomia in these infants. Our objective was to test the hypothesis that human insulin is associated with lower insulin antibody levels and less macrosomia than is animal species insulin.

STUDY DESIGN

Forty-three insulin-requiring pregnant (< 20 weeks' gestation) women, previously treated with animal insulin, were randomized to human and animal insulins and studied at weeks 10 through 20, 24, 28, 32, 36, and 38, at delivery, and at 3 months post partum. Infant blood was drawn at delivery (cord) and at 1 day and 3 months post partum 1 hour after a glucose-amino acid challenge.

RESULTS

Women receiving human insulin required significantly less insulin per kilogram of body weight and showed significant dampening of glucose excursions (p < 0.05 for each comparison). Infants born to mothers receiving human insulin weighed 2880 +/- 877 gm compared with 3340 +/- 598 gm for infants of women treated with animal insulin (p < 0.05). There was no difference in insulin antibody levels between groups for either mothers or infants. Infants born to mothers receiving human insulin had a 1 hour C-peptide level after the glucose-amino acid challenge at 3 months of age of 0.21 +/- 0.13 pmol/ml compared with 0.32 +/- 0.13 pmol/ml (p = 0.01).

CONCLUSION

Administration of human insulin to pregnant diabetic women has a therapeutic advantage over animal insulin, with less maternal hyperglycemia or hypoglycemia, fewer larger-for-gestational-age infants, and less neonatal hyperinsulinemia. Our data do not support the hypothesis that maternal antibodies to insulin influence infant birth weight.