Effect of Low-Dose Niacin on Glucose Control in Patients with Non--Insulin-Dependent Diabetes Mellitus and Hyperlipidemia

BACKGROUND: High doses of niacin have been shown to impair glucose control in patients with non--insulin-dependent diabetes mellitus (NIDDM). We undertook a study to determine if low-dose niacin has a similar effect. METHODS: Patients with stable NIDDM and hyperlipidemia underwent a 2-month observation phase where diet and diabetes medication were unchanged. Fasting blood sugar was determined every 2 weeks, and hemoglobin A(1c) and lipid profile was obtained at week 8. Patients then received niacin 500 mg three times daily for 2 months with fasting blood sugar measured every 2 weeks and hemoglobin A(1c) and lipid profile determined at week 16. Statistical analysis was performed using a t-test for related groups. RESULTS: Six of nine patients completed the protocol. Mean fasting blood sugar was statistically higher during niacin therapy versus baseline (131 mg/dL plus minus 27 vs. 161 mg/dL plus minus 40, p < 0.05). Two patients had an increase in fasting blood sugar exceeding 200 mg/dL. No change was noted in hemoglobin A(1c). There was a trend in a decrease in total cholesterol, low-density lipoprotein and triglyceride. High-density lipoprotein was statistically higher after niacin therapy. CONCLUSION: Low-dose niacin increases fasting blood sugar in patients with stable NIDDM.