Nutritional management of pregnancy complicated by diabetes: historical perspective

Caloric restriction in pregnant diabetic women: a review of maternal obesity, glucose and insulin relationships as investigated at the University of California, San Diego

Caloric restriction during pregnancy is contraindicated for women with a normal body mass index (BMI) of 19.8-26 kg/m2. Reduction of caloric intake in obese pregnant normal and diabetic women has been a controversial topic for many years. This paper reviews several clinical studies initiated in 1978 at the University of California, San Diego. One focus of this review concerns modest caloric reduction in obese women with gestational diabetes mellitus (GDM). Metabolic observations of diabetes during pregnancy in the past decade include extensive use of a 400 kcal isocaloric breakfast meal tolerance test to assess maternal glucose:insulin relationships and the degree of insulin resistance in obese pregnant subjects. We have previously reported that maternal hyperinsulinemia with or without maternal hyperglycemia is an important factor in fetal macrosomia. We suggest for obese pregnant diabetic women implementation of nutritional recommendations of the 1990 Committee on Nutritional Status During Pregnancy and Lactation, Food and Nutrition Board, Institute of Medicine, National Academy of Sciences that advise a lower caloric intake for obese normal pregnant women with BMIs greater than 26. In obese noninsulin-dependent diabetic women and those with GDM, we urge that a large prospective epidemiologic study be undertaken to assess the respective roles of modest maternal caloric restriction and maternal glucose:insulin relationships on neonatal and long-term longitudinal measurements of growth and development of children of diabetic mothers.

Caloric restriction in gestational diabetes mellitus: when and how much?

Variations in nutritional intake during pregnancy have measurable effects on the circulating levels of maternal nutrients, maternal weight gain, and birth weight of the offspring. A growing body of evidence indicates that alterations in maternal metabolism can also have long-term consequences in the offspring in relation to adult adiposity, glucose tolerance, and perhaps intellectual development. Therefore, recommendations for diet during pregnancy must be made with great care, and with as much scientific understanding as possible. Nutritional advice traditionally given to all pregnant women, including those with gestational diabetes mellitus (GDM) or noninsulin-dependent diabetes, does not allow for individual differences in caloric needs as a function of the degree of maternal obesity and thus, may encourage excessive weight gain. Evidence reviewed below suggests that adjusting caloric intake to meet new guidelines for weight gain during pregnancy may be advantageous in reducing maternal blood sugar and insulin levels, without producing abnormalities in other metabolic variables. Modest caloric reduction which limits excessive weight gain in the mother may also be associated with a small reduction of fetal weight. However, more stringent dietary manipulations in obese gravida should be discouraged as a routine measure until more knowledge is available from large-scale clinical trials about their effects on the entire panoply of maternal nutrients and their impact on the offspring.

Postprandial walking exercise in pregnant insulin-dependent (type I) diabetic women: reduction of plasma lipid levels but absence of a significant effect on glycemic control

In this study 42 pregnant women with type I diabetes and 28 nondiabetic controls were recruited to participate in a postprandial walking exercise program. Exercise patients were instructed to walk 20 minutes (1 mile) after each meal and were divided into two groups: group 1 were normal nondiabetic controls and group 2 were women with type I diabetes. There were two nonexercise comparison groups: group 3, nondiabetic controls, and group 4, women with type I diabetes. Diabetic women were followed weekly in an intensive perinatal program. Glycemic control was assessed by serial hemoglobin A1 concentration measurements, home blood glucose monitoring, 24-hour glucose profiles, and 24-hour quantitative urinary glucose loss. Glycemic control was modestly but not significantly superior in the diabetic exercise group 2 compared with the diabetic nonexercise group 4. Exercise was associated with lower fasting cholesterol and triglyceride values in both controls and diabetic women, with significantly lower fasting plasma triglyceride levels in the diabetic exercise group (p less than 0.02). There were no adverse effects of postprandial walking exercise in mothers or infants.

Gestational diabetes: maternal response to diet and insulin therapy as reflected by glycosylated hemoglobin concentration

To assess the effects of diet and insulin therapy on pregnancy complicated by gestational diabetes, glycosylated hemoglobin concentration was determined longitudinally in 32 women. Diet was instituted when a diagnosis of gestational diabetes was made and was supplemented with insulin for fasting hyperglycemia. At initial presentation, glycosylated hemoglobin concentration was increased in the 18 women who required insulin compared with the 14 women managed by diet alone (7.1% +/- 0.2% versus 6.2% +/- 0.2%, mean +/- SEM, p less than 0.01). Diet had no effect on glycosylated hemoglobin concentration that remained elevated to 6.1% +/- 0.3% compared with the glycosylated hemoglobin concentration of 5.6% +/- 0.2% for pregnant nondiabetic women (p less than 0.01). Insulin resulted in a decrease in glycosylated hemoglobin concentration within 3 to 5 weeks (p less than 0.05). After 7 to 9 weeks of insulin and diet, the glycosylated hemoglobin concentration in women with fasting hyperglycemia was the same as the glycosylated hemoglobin concentration in women who were managed by diet alone.

Management of diabetes mellitus in pregnancy

During the past decade, our major objective in the management of pregnancies complicated by diabetes mellitus has become normalization of maternal and, therefore, fetal glucose levels. For most women with insulin-dependent diabetes, this goal may be achieved through the use of multiple insulin injections combined with an appropriate dietary intake. The results of such therapy can now be accurately assessed by means of home glucose monitoring. Patients with gestational diabetes can be properly treated only if they are first identified. Therefore, all pregnant women should be tested for this disorder because screening based on past obstetric history or clinical criteria alone may miss up to 50% of patients with gestational diabetes. Between 1980 and 1984, the perinatal mortality rate reported in the American literature for more than 800 insulin-dependent patients was 21 per 1000, with more than 50% of these deaths resulting from major malformations. Such data emphasize the need to achieve maternal euglycemia before conception, as poor maternal control has been associated with teratogenesis. Prepregnancy assessment should also include a thorough evaluation of maternal vasculopathy.