Objectives: Obesity, hypertension and diabetes are closely associated with endometrial cancer (EC). This study evaluates the relationship between diabetes and risk of EC on the basis of obesity.
Methods: A case control study was carried out in Mexico City from 1995 to 1997. Eighty-five histologically confirmed cases were compared with 668 population-based controls obtained through frequency matching. Diabetes status, weight, height and other factors were determined through personal interviews among both cases and controls.
Results: Compared to women without diabetes, those with diabetes had an adjusted odds ratio of 3.6 (95% CI = 1.7, 7.4) for EC. This association was modified by body mass index (p interaction < 0.001). Compared to non-overweight and non-diabetic women, non-overweight (OR = 3.9. 95% CI = 0.88, 18.0) and overweight (OR = 5.9, 95% CI = 1.6, 21.1) diabetic women had a non-significant elevated risk of EC. However, elevated risk estimates were observed for obese diabetic women (OR = 8.0, 95% CI = 2.8, 22.7).
Conclusions: Our results strongly suggest an interaction effect between obesity and diabetes that significantly increases the risk of EC. This, in turn, may explain the growing number of new EC cases recently observed in developing countries with reduced birth rates and an increased incidence of both obesity and diabetes mellitus.