Vitamin D, parathyroid hormone levels and insulin sensitivity among obese young adult Saudis.

OBJECTIVES: To determine alterations of vitamin D and parathyroid hormone levels and their relationship to insulin resistance among a sample of healthy young adult obese Saudis and to identify factors that might predict these alterations. METHODS: Age and gender matched obese young (aged 18-25 years) adult Saudis (N = 76) with body mass index of > or = 30 and their lean controls (N = 84) were recruited after fulfilling exclusion and inclusion criteria from attendees of health facility at King Faisal University, Saudi Arabia. Selected participants were invited to a personal interview to gather information regarding socio-demographics. Fasting blood samples were assessed for the following essays: serum calcium, 25 OH vitamin D, inorganic phosphorus, intact parathyroid hormone (iPTH), serum insulin, fasting glucose, renal and liver function tests. RESULTS: Vitamin D levels were significantly higher in lean controls, and showed significant decline in relation to obesity classes, hypovitaminosis D was found in 30% (38.2% obese vs. 22.7% in lean) and deficiency in 17.5% of subjects; (19% vs. obese 15.8%). iPTH was significantly higher in obese subjects. Secondary hyperparathyroidism was found in 48.1% (60.5% obese vs. 36.9% controls). Regression analysis showed that body mass index, serum calcium and creatinine levels were the main predictors for vitamin D level. Vitamin D is positively associated with fasting blood sugar (r = -.133, P = 0.09) and beta cell function index (r = .192, P = 0.08), negatively associated with HOMA-IR (r = -.122, P = .34) but without statistical significance after controlling of possible confounders. CONCLUSION: Vitamin D level among young adult Saudi obese is negatively associated by body mass index and classes of obesity. Negative associations between vitamin D, iPTH levels and HOMA-IR exist but without statistical signifcance.

Relationship between oxidative stress, ferritin and insulin resistance in sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) is a hereditary hemoglobinopathy characterized by hemolytic anemia. The oxidative phenomena play a significant role in its pathophysiology. Blood transfusions are a therapeutic mainstay in SCD and repeated transfusions can result in iron overload. There is little direct information available to confirm the correlation between the oxidative stress, iron overload and insulin resistance in SCD patients. OBJECTIVE: To investigate the relationship between iron overload, the disorders of antioxidants and insulin levels in blood of SCD patients and their matched controls. METHODS: The antioxidant activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as the malondialdehyde (MDA, the membrane lipid peroxidation products) and carbonyl contents (the oxidative products of proteins) were estimated spectrophotometrically in erythrocytes of patients and control subjects of matched sex and ages. In addition, fasting blood glucose (FBG), ferritin and insulin levels were estimated in the sera of the same subjects. RESULTS: The mean activity values of SOD, CAT and GSH-Px were significantly decreased, whereas the average values of MDA and carbonyl contents were significantly increased in erythrocytes of SCD patients in comparison to the corresponding values of the control subjects. The average levels of FBS, ferritin, insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were significantly elevated in the sera of SCD patients as compared to the controls. In addition, both serum ferritin, and oxidative products (expressed as MDA and carbonyl levels) were significantly correlated with blood glucose, insulin level, and HOMA-IR. CONCLUSION: These findings may explain the role of elevated ferritin and oxidative products (i.e. MDA & carbonyl contents) in the development of insulin resistance and high glucose levels in SCD patients.