Purpose: Inflammatory contributions from diet and adiposity may interact with respect to the development of type 2 diabetes mellitus (T2DM). We investigated the degree to which adiposity modified the association between dietary inflammatory potential and incident T2DM.
Methods: Data from 6,016 US men in the Aerobics Center Longitudinal Study who completed a 3-day diet record were used. The inflammatory potential of diet was characterized by the Dietary Inflammatory Index (DII®), and adiposity was assessed with body mass index, waist circumference, body fat percentage (BF) and waist-to-height ratio. Inverse probability weights were used in modified Poisson regression models to examine whether adiposity modifies the relationship between the DII and T2DM, while accounting for selection bias from participants who were lost to follow-up.
Results: There were 336 incident cases of T2DM after a mean follow-up of 6.5 years. DII scores were not significantly associated with T2DM incidence in multivariable models, but point estimates were consistently elevated across increasing DII quartiles compared to the most anti-inflammatory DII quartile. In the model that evaluated BF, the term for overall effect modification was significant (p = 0.02), but there was no evidence of effect modification on the multiplicative and additive scales when examined further. Effect modification was not present for any other adiposity measures.
Conclusions: We did not observe evidence that a pro-inflammatory diet, as measured by the DII, is associated with incidence of T2DM, nor evidence that adiposity modifies a potential relationship. Further investigation is needed in larger cohorts with longer follow-up.
Keywords: Adiposity; Dietary pattern; Effect modification; Epidemiology; Inflammation; Obesity.