Incidence and severity of gestational diabetes mellitus according to country of birth in women living in Australia

Gestational diabetes among Bedouins in southern Israel: comparison of prevalence and neonatal outcomes with the Jewish population

Differences in the prevalence of gestational diabetes mellitus (GDM) have recently been reported between various ethnic populations. In the Negev region of Israel, a universal free screening programme for GDM was implemented in 1985. Between 1 March 1987 and 31 July 1988 11,003 deliveries occurred at the Soroka Medical Center, which provides free delivery and postnatal care to the whole Jewish and Bedouin population of the region. GDM was found in 5.7% of Jewish and in 2.4% of Bedouin women (odds ratio, 2.3, 95% confidence interval (CI) 1.8-2.9; P < 0.0001). Ethnicity was unrelated to maternal outcome, perinatal mortality or to any of the examined morbidity conditions of the newborn. The incidence of major congenital malformations was significantly higher in Jewish than in Bedouin infants of GDM women (Fisher's Exact Test, P < 0.03). Conversely, Jewish infants had fewer minor congenital anomalies (odds ratio 0.26, 95% CI 0.09-0.73). In a multivariate logistic regression model, gestational age, mode of delivery and insulin requirement during pregnancy were the only factors independently associated with neonatal morbidity. The results of this study suggest that in our health care system, among women with GDM ethnicity is not associated with an excess of unfavourable maternal or infant outcomes.

Amylin regulation of fuel metabolism

The 37-amino acid amylin, co-secreted from the pancreatic beta cells with insulin in response to nutrient stimuli has actions in a number of tissues of metabolic interest. In muscle it opposes glycogen synthesis and activates glycogenolysis, an action likely to underly its stimulation of lactate flux. Amylin therefore appears to have the effect of transposing carbon from peripheral stores to the liver, where it is made available for hepatic synthesis of glucose, glycogen, and lipid. While amylin induces insulin resistance in skeletal muscle, it does not oppose insulin action in fat and may therefore favor fuel deposition in this tissue. Amylin acts on the beta cell to inhibit insulin secretion. Relative impairment of insulin secretion, muscle insulin resistance, relatively preserved insulin sensitivity in fat, increased lactate turnover, and increased hepatic glucose production are features of insulin resistance and early non-insulin-dependent diabetes mellitus. Amylin is elevated in these dysfunctional metabolic states and may be involved in their pathogenesis.

Gestational diabetes: a challenge for the future

It is well established that pregnancy is associated with temporary changes in maternal metabolism which include a decrease in maternal insulin sensitivity to values similar to those associated with Type 2 diabetes. Fasting glucose concentrations fall throughout pregnancy, postprandial values rise. The maintenance of glucose tolerance in pregnancy requires a two- to three-fold increase in postprandial maternal insulin secretion. Glucose intolerance develops in women unable to compensate for the metabolic changes incurred by pregnancy. Increasing maternal hyperglycaemia is associated with increasing pregnancy morbidity and an increased likelihood of subsequent diabetes in the mother. In addition, maternal hyperglycaemia has a direct effect on the development of the fetal pancreas and is associated with an increased susceptibility to future diabetes in the infant, an effect which is independent of genetic factors. Gestational diabetes mellitus (GDM) is defined as glucose intolerance first recognized in pregnancy, and by definition includes a small number of women with previously unrecognized diabetes or impaired glucose tolerance (IGT). Figures on the prevalence of GDM vary between maternity units, depending on screening methods and the ethnic distribution of the populations. However, in a comprehensive study of a multi-ethnic antenatal population in inner London, UK it was found that only 2% of pregnant women develop significant glucose intolerance. Obstetricians and physicians debate the importance of identifying this 2% of women. The lack of agreed criteria for diagnosing gestational diabetes and the questionable obstetric benefits of treating all women with mild disturbances of glucose tolerance in pregnancy has resulted in few UK centres undertaking universal screening for GDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Why do Asian-born women have a higher incidence of gestational diabetes? An analysis of racial differences in body habitus, lipid metabolism and the serum insulin response to an oral glucose load

We have observed a higher incidence of gestational diabetes (GDM) in Asian-born than in Caucasian women. Body habitus, serum lipid levels and the serum insulin response to a glucose load in pregnancy were compared in 15 women with normal glucose tolerance, 16 Caucasian women with GDM and 19 Asian-born women with GDM. Caucasian women with GDM, unlike Asian-born women with GDM, were obese compared with control women as measured by body mass index (p = 0.022). Both groups of GDM women had similar patterns of insulin response to oral glucose with a delayed insulin peak and an elevated 2-hour insulin level (p = 0.0021). In addition, the insulin response per unit of glycaemic stimulus (incremental insulin area/incremental glucose area at 1 hour) was reduced in both GDM groups (p = 0.035). Fasting serum triglyceride levels were higher in women with GDM although this was only significant in the Caucasian group (p = 0.014). Asian-born women with GDM had significantly lower (p = 0.041) serum cholesterol levels than Caucasian women with GDM. There was a significant correlation (p = 0.025) between glucose tolerance (area under the curve) and fasting serum triglyceride values. The relationship between lipid and carbohydrate metabolism in Asian-born and Caucasian women in pregnancy requires further investigation.

Gestational diabetes in twin pregnancy: prevalence and long-term implications

During the period 1971-1991 at the Mercy Hospital for Women, gestational diabetes (GDM) was diagnosed in 3,447 of 61,914 tested singleton pregnancies (5.6%) and 59 of 798 tested twin pregnancies (7.4%, p = 0.025). A difference was apparent in the period 1971-1980, when the prevalences of GDM in singleton and twin pregnancies were 3.0% and 5.6% respectively (p = 0.012), but not in the period 1981-1991 when the corresponding prevalences were 7.4% and 8.4% (p = 0.36). Of the 59 patients in whom a diagnosis of GDM in a twin pregnancy was made, 27 attended the follow-up programme. These patients were matched to a control group of 27 patients who had GDM in a singleton pregnancy with similar characteristics for known risk factors for the development of permanent diabetes mellitus. On WHO criteria diabetes mellitus occurred in 5 (18.5%) of the subjects and 2 (7.4%) of the controls (p = 0.21). The difference in prevalence of GDM in twin and singleton pregnancies is less now that the overall prevalence of the disease has more than doubled (1971-1980 versus 1981-1991). Although the increased rate of permanent diabetes mellitus after twin pregnancy is not statistically significant, it would seem wise to make a special effort to enroll these women in the follow-up programme.

Excessive birth weight and maternal glucose tolerance--a 19-year review

The incidence of birth-weight of 4,540 g (10 lb) or more rose from 0.87% in the years 1971 to 1977 to 1.16% in the 12 years from 1978 to 1989 with a concomitant increase in hyperglycaemia in our antenatal population. The relationship between excessive birth-weight and maternal glucose tolerance was investigated in the light of these observations. The results from glucose tolerance tests performed routinely during the pregnancies of 510 women who delivered infants with a birth-weight of 4,540 g or more were compared with those from a control series of 5,003 women with consecutively tested pregnancies. Glucose tolerance in subsequent pregnancies was also compared with the control series, and in 1991 the study group women were investigated for emergence of permanent diabetes mellitus. Excessive birth-weight was associated with maternal hyperglycaemia (p < 0.05) but not with gestational diabetes; 79% of infants with birth-weight > or = 4,540 g were born to mothers who were not hyperglycaemic. There was no increase in glucose intolerance in subsequent pregnancies in the study group and only 2 of 49 women with follow-up testing had diabetes mellitus. Birth-weight > or = 4,540 g occurred in 1.1% of the total population and 1.1% of women with gestational diabetes, and was related to maternal hyperglycaemia in about 1 in 5 cases. The increased incidence of excessive birth-weight infants was not related to the increased incidence of gestational diabetes in our pregnant population. Birth-weight > or = 4,540 g had a poor association with later development of diabetes.