A two year observational study of nicotinamide and intensive insulin therapy in patients with recent onset type 1 diabetes mellitus

Background and Aims: A number of trials have evaluated residual beta-cell function in patients with recent onset type 1 diabetes mellitus (DM1) treated with nicotinamide in addition to intensive insulin therapy (IIT). In most studies, only a slight decline of C-peptide secretion was observed 12 months after diagnosis; however, no data is available on C-peptide secretion and metabolic control in patients continuing nicotinamide and IIT for up to 2 years after diagnosis. Patients and Methods: We retrospectively analysed data from 25 patients (mean age 14.7 years ± 5 SD) with DM1 in whom nicotinamide at a dose of 25 mg/kg b. wt. was added from diagnosis (<4 weeks) to IIT (three injections of regular insulin at meals + one NPH at bed time) and continued for up to 2 years after diagnosis. Data were also analysed from patients (n = 27) in whom IIT was introduced at diagnosis and who were similarly followed for 2 years. Baseline C-peptide as well as insulin dose and HbA 1c levels were evaluated at 12 and 24 months after diagnosis. Results: In the course of the follow-up, patients on nicotinamide + IIT or IIT alone did not significantly differ in terms of C-peptide secretion (values at 24 months in the two groups were 0.19 ± 0.24 nM vs 0.19 ± 0.13 nM, respectively). Insulin requirement (0.6 ± 0.3 U/kg/day vs 0.7 ± 0.2 U/kg/day at 24 months, respectively) did not differ between the two groups. However, HbA 1c was significantly lower 2 years after diagnosis in patients treated with nicotinamide + IIT (6.09 ± 0.9% vs 6.98 ± 0.9%, respectively, p <0.01). No adverse effects were observed in patients receiving nicotinamide for 2 years. Conclusion: Implementation of IIT with the addition of nicotinamide at diagnosis continued for 2 years improves metabolic control as assessed by HbA 1c. In both nicotinamide and control patients, no decline in C-peptide was detected 2 years after diagnosis, indicating that IIT preserves C-peptide secretion. We conclude that nicotinamide + IIT at diagnosis of DM1 prolonged for up to 2 years can be recommended, but longer follow-up is required to determine whether nicotinamide should be continued beyond this period. © Freund Publishing House Ltd., London