Effects of nicotinamide and intravenous insulin therapy in newly diagnosedtype 1 diabetes

OBJECTIVE - To investigate the effect of intravenous insulin therapy combin ed with nicotinamide in the metabolic control and beta-cell function of new ly diagnosed type 1 diabetic subjects in comparison with intensive insulin therapy and nicotinamide alone. RESEARCH DESIGN AND METHODS - A total of 34 newly diagnosed type 1 diabetic patients were included. After the correction of initial metabolic disturba nces, subjects were randomly assigned to the following three groups within 72 h after admission: I) intensive insulin therapy + placebo (C) (n = 12); 2) intensive insulin therapy + nicotinamide, 700 mg three times a day (NIC) (n = 11); and 3) 72-h intravenous insulin followed by intensive insulin th erapy + nicotinamide, 700 mg three times a da) (NIV) (n = II). The subjects were monitored for 12 months. GAD, tyrosine phosphatase antibodies, and in sulin autoantibodies were measured. C-peptide was measured basally and afte r 2, 4, 6, 8, and 10 min of 1 mg intravenous glucagon. HbA(1c), glucagon, a nd antibody measurements were determined initially and at 1,3, 6, 9, and 12 months. RESULTS - HbA(1c) values declined to normal after treatment was initiated i n all groups and remained not significantly different during the follow-up period. We did not End differences between experimental (NIC and NIV) and p lacebo (C) groups in terms of beta-cell function, considering basal or gluc agon-stimulated C-peptide (maximal stimulated C-peptide and area under the curve [AUC] of C-peptide) values during the follow-up period. After por,lin g data From the NIC and NIV groups (both including nicotinamide) and compar ing it with data from the C group, the results remained unchanged. At diagn osis, GAD positivity) was observed in 10 of 12, 8 of Il, and 10 of 11 subje cts (NS) in the C, NIC, and NIV groups, respectively and 1A2 positivity was observed in 3 of 12, 4 of 11. and 4 of 11 subjects (NS) in the C, NIC, and NIV groups, respectively. Antibody titers displayed a similar behavior in all groups during the follow-up period. CONCLUSIONS - Our pilot study failed to demonstrate that the addition of 72 -h intravenous insulin and nicotinamide to conventional intensive insulin t herapy produces any beneficial effect in newly diagnosed type 1 diabetic su bjects in terms of beta-cell function and metabolic control.