Gestational diabetogenesis: quantitative analyses of glucose-insulin interrelationship between normal pregnancy and pregnancy with gestational diabetes

Extracellular vesicle-mediated targeting strategies for long-term health benefits in gestational diabetes

Extracellular vesicles (EVs) are critical mediators of cell communication, playing important roles in regulating molecular cross-talk between different metabolic tissues and influencing insulin sensitivity in both healthy and gestational diabetes mellitus (GDM) pregnancies. The ability of EVs to transfer molecular cargo between cells imbues them with potential as therapeutic agents. During pregnancy, the placenta assumes a vital role in metabolic regulation, with multiple mechanisms of placenta-mediated EV cross-talk serving as central components in GDM pathophysiology. This review focuses on the role of the placenta in the pathophysiology of GDM and explores the possibilities and prospects of targeting the placenta to address insulin resistance and placental dysfunction in GDM. Additionally, we propose the use of EVs as a novel method for targeted therapeutics in treating the dysfunctional placenta. The primary aim of this review is to comprehend the current status of EV targeting approaches and assess the potential application of these strategies in placental therapeutics, thereby delivering molecular cargo and improving maternal and fetal outcomes in GDM. We propose that EVs have the potential to revolutionize GDM management, offering hope for enhanced maternal-fetal health outcomes and more effective treatments.

The phytoestrogen, quercetin, in serum, uterus and ovary as a potential treatment for dehydroepiandrosterone-induced polycystic ovary syndrome in the rat

The exact mechanisms of polycystic ovary syndrome (PCOS) are unknown and there is no effective cure for the disease. The aim of this study was to evaluate the alterations in serum oestradiol and adiponectin levels and in the expression of some important genes in the uterine and ovarian tissues of PCOS rats. The therapeutic effect of quercetin on PCOS was also assessed. Rats were divided into five groups: control, ethanol, quercetin (Q), PCOS and PCOS+Q. After 30 days of oral treatments, the rats' ovaries and uteri were removed and nesfatin-1, aromatase and adipoR1 expressions were quantified with real-time polymerase chain reaction. Serum adiponectin and oestradiol levels were evaluated using enzyme-linked immunosorbent assay technique. The results of this study showed that expression of nesfatin-1 and adipoR1 genes and adiponectin serum levels decreased in the PCOS rats, but aromatase expression and oestradiol level increased. Treatment with quercetin increased the adiponectin level and expression of adipoR1 and nesfatin-1 and decreased both the expression of aromatase and the oestradiol level. Quercetin improved PCOS by phytoestrogenic effects and mimicking oestrogen's function. Quercetin also affects important factors in both the uterus and ovary and could improve the obesity and the diabetic and infertility symptoms of PCOS.

The Utility of Exosomes in Diagnosis and Therapy of Diabetes Mellitus and Associated Complications

Diabetes mellitus and the associated complications are metabolic diseases with high morbidity that result in poor quality of health and life. The lack of diagnostic methods for early detection results in patients losing the best treatment opportunity. Oral hypoglycemics and exogenous insulin replenishment are currently the most common therapeutic strategies, which only yield temporary glycemic control rather than curing the disease and its complications. Exosomes are nanoparticles containing bioactive molecules reflecting individual physiological status, regulating metabolism, and repairing damaged tissues. They function as biomarkers of diabetes mellitus and diabetic complications. Considering that exosomes are bioactive molecules, can be obtained from body fluid, and have cell-type specificity, in this review, we highlight the multifold effects of exosomes in the pathology and therapy of diabetes mellitus and diabetic complications.

Gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is defined as glucose intolerance of various degrees that is first detected during pregnancy. GDM is detected through the screening of pregnant women for clinical risk factors and, among at-risk women, testing for abnormal glucose tolerance that is usually, but not invariably, mild and asymptomatic. GDM appears to result from the same broad spectrum of physiological and genetic abnormalities that characterize diabetes outside of pregnancy. Indeed, women with GDM are at high risk for having or developing diabetes when they are not pregnant. Thus, GDM provides a unique opportunity to study the early pathogenesis of diabetes and to develop interventions to prevent the disease.

Gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is defined as glucose intolerance of various degrees that is first detected during pregnancy. GDM is detected through the screening of pregnant women for clinical risk factors and, among at-risk women, testing for abnormal glucose tolerance that is usually, but not invariably, mild and asymptomatic. GDM appears to result from the same broad spectrum of physiological and genetic abnormalities that characterize diabetes outside of pregnancy. Indeed, women with GDM are at high risk for having or developing diabetes when they are not pregnant. Thus, GDM provides a unique opportunity to study the early pathogenesis of diabetes and to develop interventions to prevent the disease.

Postpartum care of the woman with diabetes

The postpartum period in women with diabetes or GDM allows both the physician and mother to relax from the intensive medical and obstetric management that has permitted, in most cases, a successful and joyous outcome. The role of the physician, however, must switch to a proactive and preventive mode to formulate a reproductive health plan for women with diabetes and GDM. The plan should be individualized to address glycemic management and surveillance, nutritional management, contraception prescription, future pregnancy planning, and lifestyle changes. Essential to the development of a reproductive health plan is the active participation of the patient, who through education gains an understanding of the far-reaching effects her active participation will have on her subsequent health and possibly on that of her future children.

Longitudinal changes in glucose metabolism during pregnancy in obese women with normal glucose tolerance and gestational diabetes mellitus

OBJECTIVE

This study prospectively evaluated the longitudinal changes in insulin sensitivity, insulin response, and endogenous (primarily hepatic) glucose production and suppression during insulin infusion in women with normal glucose tolerance (control) and gestational diabetes mellitus before and during a planned pregnancy.

STUDY DESIGN

Eight control subjects and 7 subjects in whom gestational diabetes mellitus developed were evaluated with an oral glucose tolerance test, an intravenous glucose tolerance test, and hyperinsulinemic-euglycemic clamp with infusion of [6,6 (2)H2 ]glucose before conception and at 12 to 14 and 34 to 36 weeks' gestation. Insulin response was estimated as the area under the curve during the intravenous glucose tolerance test. Basal endogenous glucose production was estimated from isotope tracer dilution during steady state with [6,6 (2)H2 ]glucose and suppression during insulin infusion. Insulin sensitivity to glucose was defined as the glucose infusion rate required to maintain euglycemia during steady-state insulin infusion. Body composition was estimated with hydrodensitometry. Data were analyzed with 2-way analysis of variance with repeated measures for 2 groups.

RESULTS

There were increases in first-phase (P =.006) and second-phase (P =. 0001) insulin responses in both groups with advancing gestation, but the increase in second-phase response was significantly greater (P =. 02) in the gestational diabetes mellitus group than in the control group. Basal glucose production increased significantly (P =.0001) with advancing gestation, and there was resistance to suppression during insulin infusion in both groups (P =.0001). There was less suppression of endogenous glucose production however, in the gestational diabetes mellitus group than in the control group (P =. 01). Insulin sensitivity decreased with advancing gestation in both groups (P =.0001), and there was lower insulin sensitivity in the gestational diabetes mellitus group than in the control group (P =. 04). Significant decreases in insulin sensitivity with time (P =. 0001) and between groups (P =.03) remained when the data were adjusted for differences in insulin concentration or residual hepatic glucose production.

CONCLUSION

Obese women in whom gestational diabetes mellitus develops have a significant increase in insulin response but decreases in insulin sensitivity and suppression of hepatic glucose production during insulin infusion with advancing gestation with respect to a matched control group. These metabolic abnormalities in glucose metabolism are the hallmarks of type 2 diabetes, for which these women are at increased risk in later life.

The differential effects of body fat distribution on insulin and glucose metabolism during pregnancy

OBJECTIVE

Our purpose was to investigate whether maternal obesity, or more specifically body fat distribution, is associated with alterations in carbohydrate metabolism during pregnancy.

STUDY DESIGN

A longitudinal study of oral glucose tolerance tests, insulin, C peptide, and glucagon levels during each trimester and post partum was undertaken in nine lean and 14 obese women. Obese women were divided into lower body obese (n = 6, waist/hip ratio < 0.9) and upper body obese (n = 8, waist/hip ratio > or = 0.9).

RESULTS

Fasting blood glucose levels declined with advancing gestation only in lean subjects. Upper body obese women demonstrated maximal glucose response and insulin area under the curve by the second trimester, whereas lean and lower body obese women did not until the third trimester. Insulin areas were significantly elevated in upper body obese compared with lower body obese women (second trimester, p < 0.01; third trimester, p < 0.03; post partum p < 0.05). In contrast, C peptide levels were similar in obese subgroups and were significantly elevated only when compared with those of lean women. C peptide/insulin molar ratios were lower in upper body obese women during the second trimester (4.3 +/- 0.8) and third trimester (4.2 +/- 0.7) compared with lean (6.5 +/- 1.3, 6.7 +/- 0.5) and lower body obese women (7.9 +/- 1.4, 6.5 +/- 1.4) (p < 0.01). A significant relationship between waist/hip ratio and glucose level (r = 0.70, p < 0.004) and insulin areas (r = 0.76, p < 0.001) was present in late pregnancy in obese subjects.

CONCLUSIONS

Relative hyperinsulinemia and earlier maximal glucose response in upper body obese women suggests that body fat distribution may explain the metabolic heterogeneity present in obese women during pregnancy. Body fat topography may serve as a potential marker for the early development of carbohydrate intolerance during pregnancy.

Carbohydrate metabolism during pregnancy in control subjects and women with gestational diabetes

The purpose of this study was to characterize carbohydrate metabolism associated with the development of gestational diabetes. Six control (Ctl) and ten women with gestational diabetes mellitus (GDM) were evaluated using an intravenous glucose tolerance test and hyperinsulinemic-euglycemic clamp with [6,6-2H2]glucose prior to conception (P) and at 12-14 (E), and 34-36 wk of gestation (L). There was an increase (P = 0.0001) in first-phase insulin response in Ctl (P 174 +/- 133, E 388 +/- 120, and L 587 +/- 303 microU/ml) and GDM (P 197 +/- 94, E 267 +/- 77, and L 376 +/- 162 microU/ml) but a significant (P = 0.02) lag in change in GDM with advancing gestation. Basal endogenous glucose production increased during gestation [Ctl: P 2.74 +/- 0.23, E 2.62 +/- 0.38, and L 3.14 +/- 0.36; GDM: P 2.68 +/- 0.51, E 2.78 +/- 0.45, and L 2.98 +/- 0.48 mg.kg fat-free mass (FFM)-1 x min-1; P = 0.02], but there was resistance to suppression by insulin infusion (P = 0.03) in late gestation (GDM: 0.61 +/- 0.44 vs. Ctl: 0.16 +/- 0.17 mg.kg FFM-1 x min-1). Insulin sensitivity decreased during gestation (Ctl: P 10.78 +/- 2.78, E 8.34 +/- 2.36, and L 4.75 +/- 1.22; GDM: P 7.49 +/- 2.13, E 7.40 +/- 1.45, and L 4.21 +/- 1.01 mg.kg FFM-1 x min-1; P = 0.0001) and was primarily decreased (P = 0.04) in GDM compared with Ctl from P through E. These findings closely resemble those of non-insulin-dependent, predominantly insulin-resistant diabetes, which is often a sequel of GDM.

Insulin sensitivity and B-cell responsiveness to glucose during late pregnancy in lean and moderately obese women with normal glucose tolerance or mild gestational diabetes

We used the minimal model technique to obtain concurrent measurements of whole-body insulin sensitivity and pancreatic B-cell responsiveness to glucose during the third trimester of pregnancy. Insulin sensitivity in normal pregnant women (n = 8) was reduced to only one third that of a group of nonpregnant women (n = 7) of similar age and relative weight. This marked insulin resistance was compensated by reciprocal enhancement of the first and second-phase insulin responses to intravenous glucose, which were increased threefold as compared with the nonpregnant women. Women with gestational diabetes mellitus (n = 16) had mean insulin sensitivity that was similar to that of the normal pregnant group, which indicates that insulin action was appropriate for the late phase of pregnancy in the gestational diabetic group. By contrast, the mean first-phase insulin response was significantly reduced in women with gestational diabetes mellitus, as compared with that of normal pregnant women (p less than 0.001). However, approximately one fifth of the group with gestational diabetes mellitus had first-phase responses that did not fall below the 95% confidence interval for the mean in normal pregnant women. The mean second-phase response was also lower in the group with gestational diabetes, although the difference was of borderline statistical significance (p less than 0.09). Our findings reveal the quantitative nature of the reciprocal changes in insulin sensitivity and B-cell function that normally accompany late pregnancy. They further indicate that during the third trimester, mild gestational diabetes is characterized by an impairment of pancreatic B-cell function rather than an exaggeration of the normal insulin resistance of late pregnancy.

Accelerated starvation in late pregnancy: a comparison between obese women with and without gestational diabetes mellitus

We compared the glucose, insulin, free fatty acid, and 3-hydroxybutyrate responses to a briefly extended overnight fast during the third trimester of pregnancy between two groups: obese women with normal glucose tolerance (n = 10) and age- and weight-matched women with gestational diabetes mellitus (n = 10). After a 12-hour overnight fast, plasma glucose (95 +/- 4 vs. 78 +/- 2 mg/dl; p less than 0.01), insulin (32 +/- 5 vs. 17 +/- 2 microU/ml; p less than 0.02), and free fatty acid (860 +/- 63 vs. 639 +/- 79 mmol/L; p less than 0.05) levels were higher in the patients with gestational diabetes mellitus. 3-Hydroxybutyrate levels were similar in the two groups at that time (0.23 +/- 0.04 vs. 0.18 +/- 0.03 mmol/L; p greater than 0.3). When the fast was extended to 18 hours by having the patients skip breakfast, glucose levels fell more rapidly in the group with gestational diabetes mellitus but remained elevated compared with the nondiabetic women. Insulin levels declined at a similar rate in the two groups. Free fatty acid levels did not increase significantly in the group with gestational diabetes mellitus during the extended fast. In contrast, free fatty acid levels increased by 44% in the normal pregnant women, reaching the level observed in the group with gestational diabetes mellitus after 18 hours. 3-Hydroxybutyrate levels remained virtually identical in the two groups throughout the brief fast. Thus, compared with that of normal pregnant women, the response of obese women with gestational diabetes mellitus to brief caloric deprivation during late pregnancy was characterized by a greater fall in plasma glucose values without a greater propensity to ketosis. Our findings may have important implications for the dietary management of obese patients with gestational diabetes mellitus.

Gestational diabetes in the BHE rat: influence of dietary fat

Two studies were performed to assess the effect of fat feeding on glucose tolerance before, during, and after gestation of BHE rats. In the first study 5% or 22% fat diets were fed from 3 weeks before mating until after gestation. In the second study, these diets were fed from weaning until 400 days of age. Glucose tolerance before and after gestation was not affected by diet in the short-term study. At 19 days' gestation, glucose tolerance had deteriorated in the pregnant rats that were fed with 22% fat diet. In the long-term study, abnormal glucose tolerance was observed before mating in rats that were fed the 22% fat diet. Tolerance improved during gestation and post partum, but still was not normal. Fertility and pup survival were significantly (50%) reduced in rats that were fed the 22% fat diet. These findings suggest that either short-term or long-term feeding of a 22% fat diet to BHE rats results in a model for human gestational diabetes that might be worthy of further study.

Increased risk for gestational diabetes mellitus associated with insulin receptor and insulin-like growth factor II restriction fragment length polymorphisms

Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset or first recognition during pregnancy. We have examined restriction fragment length polymorphisms (RFLPs) near "candidate diabetogenic genes" as one approach to identify molecular markers for GDM genes. Genotypes for insulin hypervariable region (HVR), insulin-like growth factor II (IGF2), insulin receptor (INSR), and glucose transporter (GLUT1) RFLPs were studied in 96 GDM and 164 control subjects, matched to GDM for race, age, and gravidity. Logistic regression analysis was used to explore the relationship between genotypes at these candidate gene loci and GDM, while adjusting for the effects of potential confounding variables. Among black subjects, the INSR allele 1 (P = 0.001) and interactions between INSR allele 1 with body mass index (BMI) (P = 0.002) and history of DM in subject's mother (P = 0.004) contributed significantly to GDM risk. Among Caucasian subjects, a similar relationship between the INSR allele 1 (P = 0.007) and INSR allele 1-BMI interactions (P = 0.011) on GDM risk were observed. In Caucasians, an additional significant risk factor was determined by an INSR allele 1-IGF2 allele 2 interaction (P = 0.018). No risk factors were identified in Hispanic subjects. These data continue to support the hypothesis that GDM is a heterogeneous disorder with respect to phenotypic and genotypic features. Furthermore, our data suggest that risk for GDM in black and Caucasian subjects is not due to obesity perse but to interactions between obesity and INSR alleles. In Caucasian women, INSR and IGF2 alleles interact to confer additional risk for GDM. Thus genes underlying susceptibility to GDM in some women may be similar to genes conferring risk to NIDDM, while in others novel genes may contribute to GDM risk.

Gestational diabetes reverses the circadian variation of plasma insulin response to intravenous glucose

Both healthy third-trimester pregnant women and a group of women with gestational diabetes failed to show a difference in glucose clearance rates when given an intravenous glucose bolus at 8 AM compared with 4 PM. The plasma insulin response in the healthy pregnant women was greater at 8 AM. In the diabetic group, the peak insulin response was greater at 4 PM, but it was more prolonged after the 8 AM tests. These alterations in plasma insulin response were especially striking in the subgroup of obese women with gestational diabetes, who demonstrated metabolic differences compared with their nonobese counterparts.

Maternal and cord blood glycated albumin and total serum proteins: correlation with maternal glycemic control and birth weight

Maternal and cord blood glycated albumin and total protein levels were measured in three groups: normal women (nondiabetic women who gave birth to infants that were normal for gestational age), test women (women who had no evidence of glucose intolerance with screening procedures and who gave birth to large for gestational age infants), and women with gestational diabetes. In all cases the cord glycated albumin and total protein levels were 20% to 30% less than the corresponding maternal levels, and no correlation could be detected between cord and maternal blood concentrations. There was no significant difference in cord and maternal glycated albumin and total protein levels among the three groups, although there was a slight upward trend detected in the test and diabetic groups. There was no significant correlation between birth weight ratio and either cord or maternal values for any of the groups except the diabetic cord samples, where a significant negative correlation between glycated albumin and total protein and birth weight ratios was found. The implications of these findings are discussed in respect to the usefulness of cord and maternal glycated albumin and total protein in retrospective screening for gestational diabetes.

Cord blood glycosylated (glycated) hemoglobin: correlation with maternal glycosylated (glycated) hemoglobin and birth weight

Maternal and cord blood glycosylated hemoglobin levels were measured by an affinity chromatographic method in three groups: normal women (nondiabetic women who gave birth to infants that were normal for gestational age); test women (women who had no evidence of glucose intolerance with screening procedures and who gave birth to large-for-gestational age infants); and women with gestational diabetes. In all cases the level of cord blood glycosylated hemoglobin was approximately 40% less than the corresponding maternal blood levels, and no correlation could be detected between maternal and cord blood concentrations. The reference range for glycosylated hemoglobin in the normal maternal population was similar to that for nonpregnant adults. There was no significant difference in cord and maternal glycosylated hemoglobin levels among the three groups, although a slight upward trend was detected in the diabetic group. There was a lack of correlation of cord and maternal glycosylated hemoglobin with birth weight in all three groups. The implications of these findings are discussed in respect to the usefulness of cord and maternal glycosylated hemoglobin in retrospective screening for gestational diabetes.

Pregnancy-associated changes in the endocrine pancreas of normoglycaemic streptozotocin-treated Wistar rats

The effect of pregnancy on pancreatic insulin content and relative B-cell volume has been studied in normoglycaemic Wistar rats treated with streptozotocin 14 days before mating. A single intravenous injection of streptozotocin (30 mg/kg body weight) caused a significant reduction of pancreatic insulin content and B-cell volume. The islet insulin content was 60% of control values. However, pregnancy-associated adaptation was preserved in these streptozotocin-treated animals. Plasma insulin levels, pancreatic insulin and B-cell volume were significantly enhanced compared with non-pregnant rats investigated on the same date. The incorporation of [3H]-thymidine into islets from pregnant rats (day 10.5) was higher than that in islets isolated from non-pregnant animals. After delivery insulin content and B-cell volume returned to pre-pregnant values. Also during a longer period after streptozotocin treatment (156 days), no measurable enhancement of B-cell volume and pancreatic insulin content was observed indicating the unresponsiveness of residual B cells to compensate spontaneously for the loss despite persisting normoglycaemia.

Effects of gestation on glucose tolerance and plasma insulin in cynomolgus monkeys (Macaca fascicularis)

Gestational alterations in carbohydrate metabolism in a group of cynomolgus monkeys were characterized by a decrease in fasting plasma glucose and by an increase in peak plasma insulin response subsequent to a glucose challenge. These changes are prominent as early as the first trimester of pregnancy. Glucose clearance rates and fasting plasma insulin did not show significant changes during gestation or post partum. Peak plasma insulin remained elevated in lactating animals studied 4 to 10 weeks post partum.

The insulin response to glucose infusion in gestational diabetes

Using a glucose infusion test insulin responses and insulin sensitivities were studied in 15 gestational diabetic women at 36-40 weeks gestation. In all women intravenous glucose tolerance had returned to normal at six weeks postpartum. Twelve women had a repeat glucose infusion test done 7-24 weeks (mean 17 weeks) postpartum. The results were compared with previously evaluated normal non-pregnant and normal pregnant standards and insulin responses below the normal 15th percentile were defined as "low". Twelve women had "low insulin responses in late pregnancy, and six had "low" insulin responses postpartum. The mean insulin sensitivity index of 1.34 +/- 1.21 (mean +/- SD) was significantly higher in the gestational diabetic group during pregnancy compared with a control pregnant group at 0.53 +/- 0.21 (p less than 0.01). The findings in this study support the hypothesis that gestational diabetes may arise in women who are unable to achieve adequate insulinogenic compensation to pregnancy. Increased insulin sensitivity in gestational diabetes may be a compensatory mechanism.

Metabolism during normal and diabetic pregnancy and its effect on neonatal outcome

Diurnal profile studies have been used to define the fetal carbohydrate and lipid substrate environment in normal and diabetic women during late pregnancy. In women with normal glucose tolerance the diurnal plasma glucose concentration was maintained within close limits (mean +/- S.D., 4.70 +/- 0.38 mmol/l) but in chemical and insulin-dependent diabetics there was a marked increase in both the mean diurnal glucose value and in the variability of the plasma glucose levels observed through the day (mean +/- S.D., 5.61 +/- 5.61 +/- 1.03 and 6.02 +/- 1.26 mmol/l respectively, P less than 0.01). No difference was observed between the peripheral insulin activity of the normal and chemical diabetic women, and the impaired glucose tolerance of the latter group was due to a deficient insulin response to goucose. The diurnal glucose variability, expressed as the standard deviation of the mean, was found to be inversely correlated with the residual C-peptide response in insulin-requiring diabetics. The mean diurnal plasma free fatty acid (FFA) concentration was slightly raised in chemical diabetic subjects compared to normal women (mean +/- S.D., 0.77 +/- 0.34 and 0.68 +/- 0.20 mmol/l respectively) but this difference was not significant. Insulin treatment produced a marked reduction in circulating FFA concentration, with a mean value in the insulin-dependent diabetic group of 0.45 +/- 0.11 mmol/l (P less than 0.001). Neonatal glucose assimilation during the first two hours of life correlated strongly with several functions of maternal carbohydrate tolerance. This was associated with higher plasma insulin concentrations at birth, and a marked tendency to hypoglycaemia in the infants of untreated chemical diabetic women. Impaired mobilization of triglyceride stores was also observed during the two hours after birth in the infants of diabetic women. This, however, appears to be due not to impaired lipolysis but to rapid re-esterification of FFA. These findings all indicate a state of functional hyperinsulinism in the infant of the diabetic women secondary to maternal hyperglycaemia.

Plasma insulin response following intravenous glucose in gestational diabetics

More insulin is needed to maintain glucose homeostasis during pregnancy. Pregnancy also has a diabetogenic effect on the mother, especially in genetically and obstetrically predisposed women. In the third trimester 195 pregnant women were screened for glucose tolerance by IVGTT (0.33 g/kg body-weight) and for plasma insulin response. In early puerperium the test was repeated. The results in gestational diabetics (k-value less than or equal to 1.0; n = 98) were to be compared to pregnant women with normal glucose tolerance (n = 97). Statistical methods (incl. discriminant analysis) were to verify differences in acute insulin release of the beta-cell and the cumulative insulin response following intravenous glucose. During the third trimester quantitatively more insulin is released when compared with early puerperium both in gestational diabetics and normal subjects (paired t-test p less than 0.01). A quantitative hypofunction of the beta-cells following intravenous glucose in gestational diabetics can be excluded. On the other hand, the most striking findings are a delayed insulin response in the initial phase of secretion (5-10 min) and significantly higher insulin levels during the late phase especially at the end of the test period (60 min) in gestational diabetics. In these cases a peripheral insulin resistance can be discussed. Hyperinsulinism is correlated to the clinical parameters overweight (greater than 10%) and the gaining of at least 12 kg of weight during pregnancy.

Effect of hormone replacement therapy on glucose tolerance in postmenopausal women

Oral glucose tolerance tests were performed on 50 symptomatic postmenopausal women before and after three months of hormone replacement therapy. All patients were randomly allocated to one of five groups treated with various synthetic or so-called naturally occurring oestrogens. Therapy produced a significant deterioration of carbohydrate tolerance with sequential preparations containing 100 microgram of ethinyl oestradiol or graduated doses of mestranol up to 50 microgram. The conjugated equine oestrogen (1.25 mg daily) and oestrogen valerate (2 mg daily) treated groups did not show abnormal glucose tolerance. The decreased glucose tolerance may be due as much to dosage levels as to any metabolic characteristics of the various oestrogens prescribed.

Gestational and pregestational diabetes: an approach to therapy

The objective of management in the pregnant diabetic patient is to achieve physiologic glucose homeostasis through the use of diet and insulin. As outlined, the numerous ancillary tests developed during the past 15 years to assist the clinician in determining impending fetal death have left much to be desired, especially where metabolic homeostasis has not been achieved prior to the thirty-sixth week of gestation. The statistics from this institution indicate that the maintenance of the plasma glucose concentration below 100 mg. per cent throughout gestation, regardless of the severity of the diabetes, all but removes the risk of maternal-fetal complications due to diabetes. The management is uniform for all patients exhibiting an abnormality of carbohydrate metabolism, and, although it is rather difficult to accept, there have been minimal neonatal complications when the protocol outlined in this presentation has been followed.

Glucagon secretion in late pregnancy and the puerperium

Fasting plasma glucagon levels in late pregnancy were not significantly changed from those of nonpregnant matched control subjects, but at 6 to 8 weeks post partum a significant decrease in fasting glucagon levels was observed. Acute elevation of plasma glucose levels (via 25 Gm. intravenous glucose loading) induced a suppression of glucagon levels. This glucose-mediated glucagon suppression appeared to be less during late pregnancy which is probably related to the smaller increments of plasma glucose following intravenous loading in late pregnancy as compared to postpartum values.