medwireNews: Research suggests that overweight and obesity per se increase the risk of diabetes in young men, even if they have no metabolic abnormalities or diabetes risk factors.
“This finding emphasizes the importance of tight follow-up of overweight and obese young adults for diabetes incidence, independent of the presence of other risk factors”, say lead study author Gilad Twig (Sheba Medical Center, Tel Hashomer, Israel) and colleagues.
The results are based on a median 6.1 years’ follow-up of 33,939 men, aged an average of 30.9 years, in the Metabolic, Lifestyle and Nutrition Assessment in Young Adults cohort. During this time, 734 new cases of diabetes emerged, and each unit increase in participants’ body mass index (BMI) was associated with a 10.6% increase in the likelihood of developing diabetes.
Metabolically healthy people were defined as those free of any National Cholesterol Education Program–Adult Treatment Panel III metabolic abnormalities, ie, components of the metabolic syndrome. This included 9183 (55%) of 16,668 normal-weight men and 4207 (32%) of 12,996 overweight or obese men.
Diabetes incidence rose in line with BMI category and number of baseline metabolic abnormalities, and was significantly higher in obese than normal-weight metabolically healthy men, at 4.34 versus 1.15 cases per 1000 person–years. Indeed, in a multivariate model that included family history of diabetes, metabolically healthy men had a significant 1.60-fold increased risk of diabetes if they were overweight and a 2.74-fold increased risk if they were obese.
The team describes this finding as “intriguing”, suggesting that “[w]hile obesity seems to mediate the incidence of diabetes, independent of the above-mentioned classic risk factors, it may still be mediated by significant insulin resistance and/or β-cell dysfunction that have not yet resulted in dysglycemia or dyslipidemia.”
The addition of baseline metabolic abnormalities increased participants’ diabetes risk, with a stronger effect in normal-weight men, at a 67% increase per abnormality, than in obese men, at a 51% increase.
Writing in Diabetes Care, Twig et al note that their findings in young men contradict some studies of middle-aged people, in whom metabolically healthy obesity was associated with a low diabetes risk.
They suggest this may be “a result of survival bias, as this group consists of men who were likely overweight or obese for many years and nevertheless have not developed diabetes or other metabolic abnormalities.”
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