Electrogustometry was performed in diabetics and the correlation between the electric gustatory threshold and clinical factors of the patients (age, disease period and diabetic complications) were evaluated (n = 50). The results obtained were as follows: 1. The electric gustatory threshold rose with aging. The patient age range for further analysis was confined to 50 approximately 69 years old (n = 34) to exclude age dependency. 2. The patients with longer disease histories tended to show a higher electric gustatory threshold, indicating that taste abnormalities in diabetics progress with disease duration. 3. Elevation of the electric gustatory threshold in diabetics was observed before onset or at the earliest stage of the three major complications (diabetic neuropathy, retinopathy and nephropatho), and the threshold rose further with the progression of diabetic complications. Thus, the electric gustatory threshold is a sensitive indicator of diabetic nephropathy and was demonstrated to be a remarkably useful indicator for the prevention of diabetic complications, since it allows detection of the three major diabetic complications at their earliest stages.