Background and aim: Orlistat and metformin are the currently used drugs for weight loss. We aimed to compare the effect of orlistat and orlistat plus metformin combination therapy on weight loss and insulin resistance in obese women.
Patients and methods: In all, 57 obese women (body mass index >/=30 kg/m(2) and normal glucose tolerance) were included. All subjects took the same content and caloric diet therapy during the study. After a month of diet period, each individual was randomly assigned to receive 360 mg orlistat per day (group 1; n=30) or 360 mg orlistat plus 1700 mg metformin per day (group 2; n=27) during the next 3 months. Body weight and insulin resistance by the homeostasis model assessment model (HOMA-IR) was measured at baseline, first month and fourth month.
Results: The mean weight loss in groups 1 and 2 was 1.36+/-0.8 kg (1.4+/-0.7%) and 1.11+/-0.7 kg (1.1+/-0.7%) from baseline to first month; 4.8+/-2.9 kg (5.28+/-3.0%) and 5.77+/-2.5 kg (6.17+/-2.9%) from first month to fourth month. Body weight was decreased in groups 1 (P< 0.001) and 2 (P< 0.001), but there was no statistically significant difference between groups. Change of HOMA-IR in groups 1 and 2 was 0.41+/-0.4 (14.9+/-10.1%) and 0.23+/-0.7 (8.16+/-12.3%) from baseline to first month; 0.49+/-0.77 (22.0+/-26%) and 0.95+/-0.88 (34.8+/-29.1%) from first month to fourth month. HOMA-IR value was decreased in groups 1 (P< 0.001) and 2 (P< 0.001) but was not different between groups during the study period.
Conclusions: Combination of orlistat with metformin did not result in an additional effect on weight loss and insulin resistance when compared to orlistat alone in our study. However, new studies which have more sample sizes and the longer study period are necessary for this purpose.