ABSTRACT
Diabetes mellitus in thalassemic major patients is common. It is usually caused by secondary hemosiderosis but a long period of insulin resistance may be occur before occurrence of overt diabetes. Zinc deficiency, also common in thalassemic patients, it seems aggravates abnormal glucose metabolism in such patients. The aim of this study was to determine serum zinc level and the contributory effect of zinc deficiency on insulin resistance and glucose intolerance in thalassemic patients in Mashhad city. This descriptive study was conducted on patients with thalassemia major. Patients with diabetes, using medicines that interfere with serum zinc [except for iron chelators] and glucose levels were excluded. Blood samples for assessment of glucose, insulin, zinc, ferretin, albumin, PT, PTT levels were obtained and a standard glucose tolerance test was performed for all patients. Insulin resistance was calculated by the homeostatic model assessment of insulin resistance [HOMA- IR]. Complete insulin resistance was defined complete in HOMA- IR>3.9, partial in HOMA- IR between 2.5-3.9 and normal in HOMA- IR<2.5. Of the 109 thalassemic patients were enrolled, 4 [3.66%] patients had impaired glucose tolerance test, 2 [1.83%] had diabetes and the remaining were normal. The prevalence of zinc deficiency was 38.5% in our patients. Mean serum zinc level in diabetic patients was 88.2 +/- 2.9 micgr/dl and in non-diabetic patients was 84.2 +/- 14.9 [p=0.34]. After exclusion of diabetic patients, insulin resistance was very high in the remaining patients. Of these, 68 [63.5%] of patients had complete insulin resistance, 31[28.9%] had partial resistance and only 8 [7.47%] had normal insulin sensitivity. No significant difference was found in ferretin levels, age and sex, between diabetic and non-diabetic patients [p=0.93, 0.35, 0.28 respectively]. A significant reverse correlation was found between serum zinc level and fasting blood sugar [p=0.002] and serum ferretin level [p=0.05]. The correlation with other variables was not significant. Zinc deficiency and insulin resistance are prevalent in thalassemic patients but no association was found between zinc deficiency and occurrence of diabetes in our study population