Aims: To assess the efficacy and tolerability of sibutramine 15 mg once daily as a weight reduction agent in overweight and obese patients (body mass index (b.m.i.) > 26 kg/m2) with type 2 diabetes when given with a customised, reduced-calorie diet, and to evaluate the influence of weight loss on diabetic control.
Methods: Randomised, placebo-controlled, double-blind, parallel-group, 12-week study conducted at two hospital-based obesity/diabetes clinics. Patients were men and women aged 30–65 years, with b.m.i. > 26 kg/m2 and ≤ 35 kg/m2 and treated or untreated type 2 diabetes diagnosed ≥ 6 months previously. Each patient was given sibutramine 15 mg or placebo once daily and advised to follow a customised diet of 500 kcal/day less than the individual's energy needs. The principal measure of efficacy was change in body weight (b.w.). Additional efficacy measurements were changes in b.m.i., body composition as measured by dual-energy X-ray absorptiometry, and change in waist and hip measurements. Changes in diabetic control were assessed by blood glucose levels fasting and after a standard test meal, fasting insulin level, and glycosylated haemoglobin level. Adverse events (AEs) were monitored at each visit, and routine laboratory safety tests were done at 4-week intervals.
Results: Ninety-one patients were randomised into the study, 44 to placebo and 47 to sibutramine 15 mg once daily. Eighty-three patients (91%) completed the study, 40 (91%) on placebo and 43 (91%) on sibutramine. Mean weight reduction from baseline was statistically significantly greater with sibutramine than with placebo at every measurement and at the end of the study (2.4 vs. 0.1 kg at week 12; p < 0.001; intent-to-treat). The proportion of patients who lost > 5% of their baseline b.w. was 19% in the sibutramine group and 0% in the placebo group (p < 0.001; 95% confidence interval: 9, 30). Patients receiving sibutramine lost significantly more fat mass compared with those receiving placebo, as a percentage (1.0% vs. 0.1%; p < 0.05) and in absolute terms (1.8 vs. 0.2 kg, p < 0.001). Loss of lean mass was not significantly different between the groups. Mean peak blood glucose concentration after a standard test meal decreased by 1.1 mmol/l in the sibutramine treatment group but increased by 0.5 mmol/l in the placebo group (p = 0.04; difference in means, 1.6, 95% confidence interval: −3.3, −0.1). Mean fasting blood glucose decreased by 0.3 mmol/l with sibutramine and increased by 1.4 mmol/l with placebo. Mean glycosylated haemoglobin levels decreased by 0.3% units with sibutramine treatment, and were unchanged with placebo. However, more sibutramine-treated patients (33%) than placebo-treated patients (5%) achieved decreases in glycosylated haemoglobin of 1% unit or more (p < 0.05). Sibutramine 15 mg was safe and well tolerated, and AEs were mostly mild or moderate in severity. No significant differences were found between treatment groups in blood pressure. No clinically significant conduction or rhythm abnormalities were observed on ECG.
Conclusions: Sibutramine 15 mg once daily with a customised, reduced-calorie diet significantly reduced weight compared with placebo in overweight and obese patients (b.m.i. > 26 kg/m2) with type 2 diabetes. Sibutramine was well tolerated, and significant improvement in diabetic control was seen in conjunction with weight reduction on sibutramine treatment.