PREVALENCE OF DIABETES-MELLITUS AND IMPAIRED GLUCOSE-TOLERANCE IN PARENTS OF WOMEN WITH GESTATIONAL DIABETES

Nuclear families of non-insulin-dependent diabetic (NIDDM) patients ar e uncommon, as usually one or both parents have died. In order to aid identification of complete nuclear families, we have ascertained the d isease process at a younger age by studying subjects with previous ges tational diabetes. One hundred women who had had gestational diabetes, age (+/- SD) 38 (6) years, were screened by fasting plasma glucose (f pg). Sixty-one were found to have either fasting hyperglycaemia (5.5 l ess than or equal to fpg < 7.8 mmol/l) or diabetes. Of these women 35 had both parents alive and the parents of 14 of these women agreed to the assessment of their metabolism by a continuous infusion of glucose with model assessment (CIGMA). Seven probands had impaired glucose to lerance (IGT) and seven were diabetic. They were age 35 (4) years and had body mass index (BMI) 26 (5) kg/m(2) The parents were aged 62 (6) years and had BMI29 (6) kg/m(2) and their affection status was defined as presence of glucose intolerance (fpg or post-infusion achieved pla sma glucose level > 2 SD of an age and obesity matched population). In the 14 families, five probands (36%) had neither parent affected, six (43%) had one parent affected and three (21%) had both parents affect ed. Only three probands had a parent with diabetes as defined by World Health Organisation criteria. We concludes that the study of women wh o have had gestational diabetes allows detection of probands with diab etes or impaired glucose tolerance, who have both parents available fo r study. A substantial proportion had neither parent affected with imp aired glucose tolerance or diabetes, similar to the nuclear families o f NIDDM patients. The results are in accord with studies of nuclear fa milies of NIDDM patients in suggesting polygenic inheritance or enviro nmental influences rather than autosomal dominant inheritance with hig h penetrance.