Insulin action and secretion independent of traditional risk factors predict new-onset type 2 diabetes in Iraqi and Swedish born citizens - The MEDIM cohort study

AIMS: Our aim was to study the incidence of type 2 diabetes in a population-based cohort of Swedish and Iraqi born individuals, focussing on traditional risk factors, insulin action, insulin secretion and ethnicity.

MATERIALS AND METHODS: The cohort consisted of 1164 Iraqi and 693 Swedish-born citizens. We investigated the association between new-onset type 2 diabetes and the predictors including lifestyle factors, metabolic risk markers, country of birth, insulin sensitivity and secretion assessed by Matsuda index with Cox regression.

RESULTS: Eighty-nine individuals were diagnosed with type 2 diabetes with a mean follow-up of 7.5 years. Both lower insulin sensitivity (ISI, HR 0.02 [0.01-0.08]) as well as insulin secretion (CIR, HR 0.13 [0.07-0.24]) at baseline predicted type 2 diabetes onset, independent of traditional risk factors. Our results were not modified by country of birth. Regarding traditional risk factors, WHR (1.05 [1.00-1.09]), blood glucose (3.27 [2.35-4.55]), LDL/HDL (1.46 [1.20-1.78]) and diastolic blood pressure (1.04 [1.00-1.07]) predicted diabetes incidence in the full model.

CONCLUSIONS: Both impaired insulin sensitivity index and corrected insulin response predicted type 2 diabetes onset, independent of traditional risk factors. We conclude that insulin secretion and action might be useful additional predictors for type 2 diabetes in populations of European and Middle Eastern ethnicities.