A family with the Bardet-Biedl syndrome and diabetes mellitus.

We studied a family with the Bardet-Biedl syndrome and diabetes mellitus. Two affected brothers and one affected sister were examined. Two older sisters with stigmata of the syndrome had died of unclear causes. The 18-year-old brother was obese, was mentally retarded, and had pigmentary retinopathy and insulin-dependent diabetes mellitus. The 16-year-old sister, who died in a diabetic coma during the course of the investigation, had polydactyly, hypogenitalism, obesity, mental retardation, and pigmentary retinopathy. The 8-year-old brother had all the features of the syndrome, but no overt diabetes mellitus. Electroretinography showed severe cone and rod dysfunction. Patients with the Bardet-Biedl syndrome should be screened for the presence of abnormalities in glucose metabolism.