RESUMO
OBJECTIVE: Poorly controlled insulin-dependent diabetes mellitus (IDDM) has been reported to be associated with an impaired metabolic availability of vitamin A. The purpose of this study was to examine vitamin A status in a select group with non-insulin dependent diabetes mellitus (NIDDM). METHODS: Participants included 106 (male, female, > 40 years) Plains Cree adults residing in central Alberta, with NIDDM (n = 59) and non-diabetic controls (n = 47). Non-fasting plasma samples were collected and concentrations of retinol, zinc, alpha-tocopherol, total protein, albumin, retinol binding protein (RBP), transthyretin (TTR), cholesterol, triglycerides, glucose, insulin, and fructosamine were determined. Multiple linear regression was used to identify predictors of plasma RBP concentration. Three repeated 24-hour recalls and a food frequency questionnaire were used to determine vitamin A intakes. RESULTS: Diabetic subjects had similar intake and plasma concentration of vitamin A compared to controls. Factors such as alpha-tocopherol, zinc, total protein, albumin, and TTR, which are known to influence vitamin A metabolism, also remained unaffected in subjects with diabetes. Plasma levels of vitamin A carrier protein (RBP), however, were elevated in diabetic subjects, possibly as a result of hyperinsulinemia. The subjects with diabetes had many characteristics of the insulin resistant syndrome, including central obesity, hypertension, and hypertriglyceridemia. Poor metabolic control, based on plasma glucose, was a significant predictor of RBP concentration in diabetic subjects. CONCLUSIONS: The plasma concentration of RBP was elevated in diabetic subjects and was associated with normal circulatory availability of retinol. The subjects with NIDDM, characterized by insulin resistance without insulin deficiency, thus, appear to be associated with normal vitamin A status.