In this article, we report the assisting effect of lithium on hypoglycemic treatment in patients with diabetes. Thirty-eight diabetic patients, 15 male and 23 female, aged 20-70 yr, 33 noninsulin-dependent diabetes mellitus (NIDDM) patients, and 5 insulin-dependent diabetes mellitus (IDDM) patients, were recruited in this study. Fasting and 1-h postprandial blood glucose (BG) profiles were undertaken from three groups of patients with diabetes before and after short-term of treatment of lithium carbonate. Group I was treated with diet only, Group II with oral hypoglycemic agents (OHA), and Group III with insulin. The fasting blood glucose (FBG) level and 1-h postprandial blood glucose (1-h PBG) level before and after treatment of lithium were: Group I: FBG: 7.67 +/- 0.48 vs 7.13 +/- 0.82; 1-h PBG 15.13 +/- 0.88 vs 10.33 +/- 0.96; Group II: FBG: 8.84 +/- 0.67 vs 6.04 +/- 0.57; 1-h PBG: 12.33 +/- 0.72 vs 9.95 +/- 0.82; Group III: FBG: 10.87 +/- 0.83 vs 6.83 +/- 0.79; 1-h PBG: 12.45 +/- 0.93 vs 9.17 +/- 1.00 mmol/L, respectively. The FBG and PBG of all three groups decreased significantly after lithium treatment, except the FBG in Group I. These data suggest that combined with other therapy, lithium could improve glucose metabolism in most patients with diabetes. Our results suggest that lithium has an assisting hypoglycemic effect on antidiabetic treatment.