Diabetes
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Study of parental transmission of diabetes provides insight into the relative contributions of underlying maternal and paternal influences. We estimated risk for type 2 diabetes and milder degrees of glucose intolerance associated with parental diabetes among subjects of the population-based Framingham Offspring Study, in which participants are primarily Caucasian and at relatively low risk for diabetes and for which both parental and offspring phenotypes were ascertained by direct examination. Parental diabetes, assessed over 40 years of biennial follow-up, was defined by use of hypoglycemic drug therapy or a casual plasma glucose level > or = 11.1 mmol/l at any examination. ⋯ For maternal diabetes to confer excess risk for mild but not overt glucose intolerance, offspring of diabetic fathers may transit abnormal to impaired glucose tolerance relatively quickly, or diabetic mothers may transmit risk for a mild slowly progressive form of abnormal glucose tolerance in addition to overt diabetes. Very high risk for abnormal glucose homeostasis among offspring with young age-of-onset maternal diabetes is consistent with hypotheses that perinatal exposures increase diabetes risk. Given equivalent risk ratios for type 2 diabetes, fathers may transmit unique paternal genetic factors of similar strength to maternal environmental factors.