PLASMA-LEVEL OF RETINOL AND OF ALPHA-TOCOPHEROL IN NON-INSULIN-DEPENDENT DIABETES-MELLITUS - ITS RELATION TO MICROANGIOPATHY OR MACROANGIOPATHY

Plasma concentration of both retinol and alpha-tocopherol were measure d by a HPLC method in 56 patients affected with non-insulin dependent diabetes mellitus (NIDDM) and in 21 age and sex-matched healthy contro ls to assess whether NIDDM and diabetic micro- or macroangiopathy coul d be associated with modified plasma levels of these vitamins. Both pl asma alpha-tocopherol or retinol and their ratios to cholesterol were similar in both controls and diabetic patients regardless of their the rapy (diet alone, oral agents or insulin). Alpha-tocopherol was signif icantly related to plasma cholesterol in the diabetic group (r=0.54; p <0.0001) and in controls (r=0.47; p<0.05), while plasma retinol was re lated only to triglycerides in control subjects (r=0.43; p<0.05). Plas ma levels of both vitamins, as well as their ratios to plasma lipids w ere similar in both groups with retinopathy or large blood vessel dise ase, compared to those without vascular complications. The group of pa tients with increased urinary albumin excretion rate (AER >20 mug/min; n=11) was characterized by a significantly higher mean plasma retinol concentration as compared to retinol plasma level of the normoalbumin uric group (n=45) (2.13+/-0.42 muM/l(SD) vs 1.75+/-0.33 muM/l; p<0.01) . This difference was independent from other variables as shown by a m ultiple regression model where age, diabetes duration, sex, body weigh t, plasma alpha-tocopherol, plasma lipids, glycated hemoglobin and blo od pressure acted as covariates. These data reveal that plasma alpha-t ocopherol and retinol are unchanged in NIDDM patients, even if affecte d by retinopathy or macroangiopathy, while diabetic nephropathy is ass ociated with an increase in mean plasma retinol.