Obesity and increased risk of type 2 diabetes mellitus : the aetiological role of depression

Obesity, defined using body mass index (BMI) values ≥30 kg/m2 (calculated as weight in kilograms divided by height in meters squared), is a serious medical condition almost entirely due to excess dietary intake. It is estimated that 205 million men and 297 million women older than 20 years worldwide were obese in 2008 [1]. The age-standardised prevalence of obesity was approximately 10% in men and 14% in women — nearly double the 1980 prevalence estimates. One of the most important consequences of high and rising trends in global obesity prevalence has been the increasing number of people developing type 2 diabetes mellitus (T2DM) [2]. Indeed, the International Diabetes Federation (IDF) reports that some 366 million people worldwide, or 8% of adults, are now estimated to have diabetes, and that lifestyle therapy should be used to achieve a healthy BMI in the prevention and management of T2DM [3]. The rising health and economic burden of T2DM disproportionately affect older, obese, and physical inactive people [4], as well as those with depression [5]. Reliable information about the aetiological role of depression in obesity and consequential T2DM could lead to more effective management and prevention planning, resulting in significant health and economic benefits.