Parental history of hypertension and parental history of diabetes and microvascular complications in insulin-dependent diabetes mellitus: the EURODIAB IDDM Complications Study.

Diabetic nephropathy clusters in families, suggesting an inherited predisposition. Parental history of hypertension and of Type 2 diabetes mellitus have been associated with nephropathy in offspring with Type 1 diabetes in some studies but not in others. The associations of parental history of hypertension and of diabetes with both albuminuria and proliferative retinopathy were studied in a large cross-sectional study of 3250 patients with Type 1 diabetes, from 16 European countries. Albuminuria was associated with hypertension in a parent (p < 0.01 in men, p < 0.05 in women), adjusted for age. Patients with a parental history of hypertension had a higher prevalence of hypertension (p < 0.001 in men, p < 0.01 in women) and a higher prevalence of parental diabetes (p < 0.001 in men, p < 0.001 in women). The association of albuminuria with parental hypertension was independent of parental diabetes in men but not women (OR = 1.28 in men p = 0.04, OR = 1.25 in women p = 0.09) and was not independent of hypertension in the patient him/herself in either sex. Albuminuria was associated with parental diabetes in women only (OR = 1.36, p = 0.04). This association was independent of both parental hypertension and hypertension in the patient herself. Proliferative retinopathy was not associated with parental hypertension or diabetes. The implications of these data are that both candidate genes for hypertension and Type 2 diabetes should be considered in the search for the genetic determinants of diabetic nephropathy.