La Reunion Island, a French overseas department in the Indian Ocean provides an example of rapid urbanisation and drastic changes in the way of life--from traditional to "westernized" lifestyle--over a few decades. To study the impact of this epidemiologic transition, a diabetes prevalence study was performed in 1999-2001. Fasting capillary blood glucose (cBG) and glycated hemoglobin (HbA1c) were systematically measured in a random sample of 3600 subjects aged 30-69 years. Weight, height, waist and hip circumferences were also measured to assess body mass index and waist-hip ratio. Diagnosis was assessed using an oral glucose tolerance test according to the World Health Organization recommendations in 363 subjects who had a cBG value > or =6.1 mmol/l, and/or a HbA1c value > or =6%. The overall diabetes prevalence rate was 17.7% for men and 17.3% for women, and the standardized diabetes prevalence rate was 20.1% (95% confidence interval: 18.7-21.4%). The most important morphological factor linked to Type 2 diabetes mellitus was waist-hip ratio, a marker of central adiposity, especially in women. This study confirms that Type 2 diabetes is increasing dramatically in societies in epidemiologic transition and is strongly linked to nutritional status.