Glycated haemoglobin is inversely related to serum vitamin D levels in type 2 diabetic patients.

Abstract

ObjectiveA correlation between glucose control and 25(OH)D metabolism has been suggested by previous studies. However, this correlation has not yet been evaluated considering the impact of chronic complications of type 2 diabetes, especially the presence of nephropathy. Thus, the aim of this study was to determine the correlation between A1C and 25(OH)D in a well characterized cohort of type 2 diabetic patients.Research design and methodsWe cross-sectionally examined the association between A1C and serum 25(OH) D in 715 type 2 diabetic patients attending our clinic during the years 2011-2012. The average age was 68±12 years (range 26-94 years). The relation between A1C and serum 25(OH)D levels was modelled by multiple linear regression analyses.ResultsSerum 25(OH)D levels were inversely associated with A1C levels (r = -0.116, p = .003). This relation maintains its independence in the multivariate analysis after adjusting for age, sex, A1C, BMI, treatment and duration of diabetes and nephropathy.ConclusionsIn type 2 diabetic patients, high A1C levels are associated with low concentrations of serum 25(OH)D independently of duration of diabetes, diabetic treatment and nephropathy. Future studies are needed to clarify the biological relation between glucose control and vitamin D metabolism in type 2 diabetes.