The feasibility of reducing the fasting blood glucose (FBG) level to < 6 mmol/L has been studied in all 84 maturity-onset diabetic (MOD) patients in three general practices. Only 35 (48%) were initially "well controlled" by this criterion, although 72 (86%) had no postprandial glycosuria. Seventy-one patients were monitored for 6 mo. With additional oral hypoglycemic therapy where necessary, the number of "well controlled" increased from 29 (41%) to 54 (76%), associated with a significant decrease in the hemoglobin A1. The patients were subsequently assessed at two 3-monthly intervals, and a fasting plasma glucose > 4 and < 6 mmol/l was usually maintained. All but two patients with a fasting glucose level < 6 mmol/l had fasting triglyceride concentrations < 2 mmol/l. The fasting blood glucose can be assayed in general practice with glucose-oxidase strips, and control by this means is simpler, cheaper, and more effective than regular urine glucose monitoring.