ZINC ABSORPTION IN DIABETIC PREGNANT WOMEN

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Congenital anomalies, pre-term and prolonged labor occur more frequently in both pregnant women with diabetes and in zinc deficient animals. In nonpregnant diabetics both fuel and zinc metabolism seem to be disturbed; the urinary zinc losses of diabetic patients are usually elevated several fold. It is not known if urinary zinc losses are also elevated in pregnant diabetic women when there is an increased need for zinc. Our research goal is twofold: (1) to determine if urinary zinc excretion continues to be elevated in diabetic women during pregnancy as it is when they are not pregnant, and (2) to find out if this increased urinary excretion is associated with changes in other aspects of zinc homeostasis, i.e., absorption and circulation. Three groups of 20 women each will be studied: insulin-dependent diabetic women, noninsulin- dependent diabetic women, and control women. Measurements will be made in all women at early (9-10 weeks), mid (24-26 weeks) and late (34-36 weeks) gestation, at the 12th week of lactation, and 6 months following the onset of menstruation. As many of the women as possible will also be studied prior to conception. At each measurement glycemic control will be assessed from measurements of glycosylated hemoglobin, glycosylated albumin (protein), fasting plasma glucose, and urinary glucose. The urinary excretion, absorption, and plasma levels of total zinc and zinc fractions will be determined. 70Zn, a stable zinc isotope, will be used as a tracer to measure the quantity of zinc absorbed from a standard diet. It is not known why urinary zinc losses are excessive in diabetics. The amount of glycosylated protein and glycosylated amino acids in the serum and urine will be measured to determine if there is any relationship between the levels of these glycosylated products and the excess zinc loss. Also, serum insulin, glucagon, and insulin/glucagon ratios will be measured and related to urinary zinc losses. The effect of diabetes on serum, erythrocyte, arterial cord blood, and urinary metallothionein levels will also be measured. Continued losses of zinc in the urine during pregnancy without comparable increases in absorption to balance these losses may place the diabetic mother at risk for zinc depletion. In that case, further studies of the relationship between maternal zinc status and pregnancy outcome in the diabetic would be warranted.