The association between obesity and an increased risk for cardiovascular disease is well established. However, there is growing evidence that overweight patients with cardiovascular disease survive longer than do their normal weight counterparts, an effect referred to as the "obesity paradox". This study was designed to determine whether such a paradox exists among patients with diabetes mellitus (DM).

Patients with known type II DM diabetes, followed in a British clinic, were enrolled in an electronic database from 1995 to 2005. Data collected included comorbid conditions, age, diabetes history and duration, smoking history, height, weight and blood pressure, collected at the time of the initial visit. This cohort was followed for clinical events until 2011. The primary outcome measure was all-cause mortality, with the secondary outcome being hospitalizations for cardiovascular events.

A total of 10，568 patients with an average age of 63 years were followed for an average of 10.6 years. Overweight or obese patients had a higher rate of cardiac events requiring hospitalizations than did those with normal weight. However, the risk for cerebrovascular accidents was greater only in those with a body mass index of 30 to 34.9 kg/m² and among those in the 57 to 67 year age group. Assessment of mortality risk of those hospitalized for these events revealed a survival advantage for higher body mass index categories (P<0.001). A Cox regression analysis demonstrated that those who were overweight had a reduced mortality risk as compared to normal weight individuals, while those who were obese had a similar mortality risk as those with normal weight. The lower mortality risk conferred by being overweight or obese developed around age of 60 years.

This study of patients with type II diabetes found that being overweight or obese was associated with a higher risk of nonfatal cardiovascular events, but not a higher risk of mortality.