Urinary albumin excretion rate (AER) was measured in non-diabetic controls (n = 143) and newly diagnosed impaired glucose tolerant (IGT, n = 64) and non-insulin-dependent (type 2) diabetic patients (n = 146). AER progressively increased from non-diabetic [3.7 (1.1-51.3) micrograms/min, median (5-95th centile)] to IGT [4.8 (1.3-53.7)] and diabetic [7.3 (1.4-91.6)] groups. Eight percent of non-diabetic, 19% of IGT and 23% of type 2 diabetic patients showed 'microalbuminuria' (AER, 20-200 micrograms/min) (non-diabetic vs diabetic P less than 0.01, non-diabetic vs IGT NS, IGT vs diabetic NS). AER was directly related to waist-hip ratio (P less than 0.001) and HbA1 (P less than 0.01) in diabetic patients; 80% of diabetic patients with microalbuminuria were men (P less than 0.06 compared to 'normoalbuminuric' diabetic patients). Association of AER with waist-hip ratio was present in men as well as women. Thus, in the newly diagnosed type 2 Indian diabetic patients AER is associated with central obesity in addition to its well known association with hyperglycaemia. Our findings offer a possible explanation for the increased risk of proteinuria in diabetic men than in women because men are centrally more obese. It could also explain previous reports of higher AER in migrant Asian diabetic patients in the U.K. compared to native white Caucasian diabetic patients because Asians are known to be more centrally obese.