Estimated insulin sensitivity predicts incident micro- and macrovascular complications in adults with type 1 diabetes over 6 years: the coronary artery calcification in type 1 diabetes study.

OBJECTIVE: Reduced insulin sensitivity (IS) is well documented in type 1 diabetes (T1D) and may contribute to vascular complications. We examined the association of estimated IS (eIS) with incident macro- and microvascular complications in adults with T1D in the prospective CACTI study.
METHODS: Participants (N=652) were 19-56 years old at baseline and re-examined 6.2±0.6years later. Urinary albumin excretion was measured, and categorized as microalbuminuria or greater. Diabetic retinopathy (DR) was based on self-reported history, proliferative DR (PDR) as history of laser eye therapy and coronary artery calcium (CAC) was measured using electron-beam CT. Progression of CAC was defined as a change in the square root transformed CAC volume score of ≥2.5. IS was estimated (eIS) by an equation derived from clamp studies. Predictors of each complication were examined using stepwise logistic regression and subjects with complications at baseline excluded. Age, T1D duration, sex, HbA1c, SBP, LDL-C, and eIS were considered for inclusion.
RESULTS: Greater eIS at baseline predicted lower odds of developing albuminuria (OR: 0.67, 95% CI 0.51-0.88), DR (OR 0.79, 0.64-0.97), PDR (OR: 0.76, 0.57-0.99) and CACp (OR: 0.71, 0.60-0.85) in multivariable models.
CONCLUSIONS: Greater eIS conferred protection from the development of vascular complications over 6-years in T1D.