Insulin resistance and vitamin D deficiency in patients with chronic kidney disease stage 2-3.

Chronic kidney disease (CKD) is associated with insulin resistance (Fliser et al. 1998, Kato et al. 2000, Chen et al. 2003) which plays an important role in the pathogenesis of cardiovascular diseases. Insulin resistance is a risk factor of metabolic syndrome (Tuttle 2005). According to WHO classsification, microalbuminuria is also a clinical criterion for the metabolic syndrome (Chen et al. 2004, Grundy et al. 2004). Analysis of a subsample of NHANES III (National Health and Nutrition Examination Survey) participants revealed a strong, positive, and significant relationship between the insulin resistance and a risk for CKD (Chen et al. 2003). Vitamin D deficiency has long been considered as a risk factor for glucose intolerance (Boucher et al. 1995, Chiu et al. 2004, Foroughi et al. 2008). An inverse correlation between serum concentration of vitamin D and insulin resistance was found in NHANES III participants (Ford et al. 2002, Chonchol and Scragg, 2007). There is an increasing evidence that vitamin D metabolism affects insulin resistance. Previous studies reported reduced serum 25(OH) vitamin D concentration in patients with CKD (Ishimura et al. 1999, Gonzales et al. 2004, Chonchol and Scragg, 2007), although the relationship between vitamin D status and insulin resistance has not been examined. Therefore, the aim of our study was to evaluate the relation of insulin sensitivity/resistance to vitamin D status in CKD patients with mild to moderate decrease in renal function.