OBJECTIVE Nicotinamide, a vitamin of the B group, has in vitro actions capable of interfering with the pathogenetic process leading to IDDM. Since 1987, several studies have evaluated nicotinamide as a means of protecting β-cells from end-stage destruction in insulin-treated patients with newly diagnosed IDDM. The aim of the study was to determine whether nicotinamide protects residual β-cell function when given at IDDM diagnosis.

RESEARCH DESIGN AND METHODS We performed a meta-analysis of the integrated parameters of metabolic control (C-peptide, glycosylated hemoglobin, insulin dose) in 10 randomized (5 of which were placebo) controlled trials conducted in recent-onset IDDM patients for a total of 211 nicotinamide-treated patients. Data on the adverse effects of nicotinamide were also collected from an additional four trials to yield a grand total of 291 nicotinamide-receiving patients.

RESULTS One year after diagnosis, baseline C-peptide was significantly higher in nicotinamide-treated patients, compared with control patients (0.73 ± 0.65 vs. 0.32 ± 0.56 ng/ml, P < 0.005). This statistical difference remained also when the five placebo-controlled trials only were considered (P < 0.05). No differences were observed in the insulin dose required or glycosylated hemoglobin values between nicotinamide and control patients. Adverse effects were reported in few patients (transient elevation of transaminase, n = 2; skin rash, n = 2; recurrent hypoglycemia, n = 2).

CONCLUSIONS This combined analysis demonstrates a therapeutic effect of nicotinamide in preserving residual β-cell function when given at IDDM diagnosis in addition to insulin. Since adverse effects were negligible, we suggest that prolonged use of nicotinamide after IDDM diagnosis should be tested to see whether residual β-cell function can be preserved for longer periods.