Ectopic fat obesity presents the greatest risk for incident type 2 diabetes: a population-based longitudinal study

Obesity is usually evaluated based on BMI, however more and more research is showing that the distribution of fat within the body is important in determining the harmful metabolic effects of obesity.

In this historical cohort study, conducted in Japan, and published in the international journal of obesity, the authors set out to determine the relationship between different phenotypes of obesity and the onset of type 2 diabetes. The authors used three phenotypes, obesity, visceral fat obesity and ectopic fat obesity; defined as body mass index >25 Kg/m2, waist circumference >90cm in men or >80cm in women, and having fatty liver diagnosed by abdominal ultrasound. Ectopic fat is defined as extra adipose tissue in locations not originally associated with adipose tissue storage. The study included 15,464 participants, who were divided into 8 groups, depending on the absence or presence of each phenotype.

They found that obesity and visceral fat alone had very little effect on the risk of incident type 2 diabetes and that the presence of ectopic fat obesity presented the greatest risk of developing type 2 diabetes. Several studies have shown before that increased adiposity in the liver leads to disrupted metabolic function, including glucose control, however this is the first study to directly compare phenotypes and assess risk. Although there were limitations to this study, the data suggests that body composition analysis should be considered when assessing a patient’s risk of obesity related disease.