Circulating Alpha-Tocopherol and Insulin Sensitivity Among Older Men With Chronic Kidney Disease.

Objective Insulin resistance is common in individuals with chronic kidney disease (CKD) and may be partly explained by modifiable risk factors. In the general population, vitamin E supplementation has been suggested to improve both insulin sensitivity and secretion. We here explore the potential role of vitamin E as a modifiable risk factor for insulin resistance among individuals with CKD. Design Observational study. Setting A total of 273 nondiabetic men aged 70 to 71 years with CKD defined as either cystatin C estimated glomerular filtration rate 2 or urinary albumin excretion rate ≥ 20 mg/minute from the third examination cycle of Uppsala Longitudinal Study of Adult Men. Subjects A total of 273 nondiabetic men aged 70 to 71 years with CKD defined as either cystatin C estimated glomerular filtration rate 2 or urinary albumin excretion rate ≥ 20 μg/minute. Methods Serum α-, β-, and γ-tocopherol concentrations were measured by high-performance liquid chromatography and expressed as μmol/total serum cholesterol and triglycerides (in mmol). Dietary vitamin E intake was estimated from 7-day food records. Main Outcome Measure Insulin sensitivity index (M/I ratio) was measured by hyperinsulinemic-euglycemic glucose clamps. Univariate and multivariate regression models were fitted to assess the association between M/I and circulating concentrations of tocopherols. Results The mean serum concentration of α-, β-, and γ- was 37.4 ± 6.58, 0.89 ± 0.23, and 4.32 ± 1.69 μmol/mmol, respectively. Median dietary vitamin E intake was 6.14 (interquartile range, 5.48-6.82) mg/day. In crude and fully-adjusted multivariate regression analyses, serum α-tocopherol levels were directly and strongly associated with M/I (standard β = 0.17, P  = .003). No such association was observed for dietary vitamin E, serum β-, and γ-tocopherol concentrations. Conclusions Serum α-tocopherol concentration associates with insulin sensitivity in nondiabetic older men with CKD.