Is incident type 2 diabetes associated with cumulative excess weight and abdominal adiposity? Tehran Lipid and...

To examine the association of the risk of incident type 2 diabetes (T2D) with cumulative excess weight (CEW) and cumulative excess waist circumference (CEWC) scores.

Adults participants without T2D (n = 4635) aged  ≥20 years were included in the study. The differences between the body mass index (BMI) and waist circumference (WC) values and their normal references were calculated until the incident T2D. The CEW and CEWC scores represent the accumulation of BMI and WC deviations from normal values over time, i.e. (kg/m² × years and cm × years, respectively). Time-dependent Cox models, adjusting for confounders were used to examine the association between CEW/CEWC and the risk of T2D. Further multivariate analyses were performed to examine the association of CEW and CEWC with incident diabetes in baseline BMI and WC strata.

There were 503 incident cases of T2D over a median follow-up 9.38 years. The multivariate sex adjusted hazard ratios (HR) per one standard deviation (SD) increase in CEW and CEWC were 1.23 (95% CI: 1.15-1.32) and 1.41 (1.25-1.59), respectively. After further adjustment for baseline BMI and WC, no significant association was observed for CEW (1.02: 0.84-1.23) and CEWC (1.09: 0.93-1.28) and incident T2D. A strong association was found between CEW and CEWC with incident diabetes among overweight (2.12: 1.20-3.74) and centrally obese individuals (1.29: 1.10-1.51), respectively.

Generally, CEW and CEWC were not associated with risk of T2D, independent of baseline values for BMI and WC, respectively. Moreover, CEW and CEWC highlighted an increased risk among overweight and centrally obese participants for T2D.