The impact of a family history of Type II (non-insulin-dependent) diabetesmellitus on the risk of diabetic nephropathy in patients with Type I (insulin-dependent) diabetes mellitus

Aims/hypothesis. There is substantial evidence for a role of genetic factor s in the development of diabetic nephropathy. In Pima Indians, a link betwe en susceptibility to diabetic nephropathy and Type II (non-insulin-dependen t) diabetes mellitus has been proposed. In this study, our aim was to exami ne the association between a family history of Type II diabetes and diabeti c nephropathy in patients with Type I (insulin-dependent) diabetes mellitus . Methods. In a cross-sectional case-control study, we assessed the prevalenc e of Type II diabetes in the parents of 137 Type I diabetic patients with d iabetic nephropathy (albuminuria > 300 mu g/min in two of three overnight u rine collections) compared with the parents of 54 Type I diabetic patients without nephropathy (albuminuria < 20 mu g/min). Results. Thirty-four (25 %) of the patients with nephropathy compared with five (9 %) of the patients without nephropathy had a parental history of Ty pe II diabetes (p = 0.019). A parental history of Type II diabetes was asso ciated with a three-fold risk [odds ratio 2.95 (95% confidence interval: 1. 03 to 8.40), p = 0.043] of diabetic nephropathy after adjustment for sex, g lycaemic control and family history of hypertension. Furthermore, there was an excess of risk factors for development of Type II diabetes (higher fast ing plasma glucose concentrations, higher prevalence of hypertension, highe r waist-hip ratio and a tendency towards more glucose intolerance) among pr eviously non-diabetic parents of patients with nephropathy. Conclusion/interpretation. Genetic or environmental factors or both related to familial Type II diabetes increase susceptibility to diabetic nephropat hy in patients with Type I diabetes.