Vitamin D deficiency and related risk factors in patients with diabetic nephropathy

OBJECTIVES To investigate serum 25-hydroxyvitamin D (25[OH]D) levels in patients with diabetic nephropathy, analyse the relationship between 25(OH)D and clinical indexes, and identify risk factors for vitamin D deficiency in diabetic nephropathy. METHODS Patients with diabetic nephropathy were sequentially enrolled and grouped according to diabetic nephropathy stage. Serum 25(OH)D levels were measured. A control group of healthy subjects was used for comparison. RESULTS Out of 240 patients with diabetic nephropathy and 60 healthy controls, 25(OH)D levels were lower in diabetic nephropathy patients than in controls, and showed a gradually decreasing trend with diabetic nephropathy stage. Serum 25(OH)D levels were significantly correlated with age, sex, diabetes history, body mass index, systolic blood pressure, albumin excretion rate (AER), estimated glomerular filtration rate, fasting blood glucose, glycosylated haemoglobin (HbA1c), haemoglobin, serum albumin, creatinine clearance rate, blood urea nitrogen and complicated diabetic retinopathy. Moreover, age, body mass index, AER, haemoglobin, and HbA1c were independent risk factors of 25(OH)D deficiency in diabetic nephropathy. CONCLUSIONS Vitamin D deficiency is prevalent in patients with diabetic nephropathy and increases in severity with diabetic nephropathy progression. Age, obesity, glucose level and renal function largely affect 25(OH)D deficiency in diabetic nephropathy.