Study Whether Serum 1,25-dihydroxyvitamin D Levels Could be an Indicator for Dysfunction of Renal Tubules

Diabetic nephropathy(DN)is a major microvascular complication of diabetes.Renal injury may be presented with the characteristics of albuminuria, and its main pathological change is glomerular sclerosis. However, both glomerular lesions such as glomerulosclerosis, glomerular basement membrane thickness and tubulointerstitial fibrosis have been found in both type 1 and type 2 diabetic patients with normal urinary albumin excretion rate, moreover the tubular injury may be the primary pathological change in diabetic renal injury not only the secondary change brought on by glomerular injury. Thus, if overt urinary albumin exists in T2DM patients, the tubular injury may be severe already. An index which is predominant, sensitive and convenient to be measured should be purposed.It is predicted that insufficient renal 1-alpha hydroxylase may play a critical role in diabetic nephropathy. Then the investigators present the presumption that the activity of renal 1-alpha hydroxylase could reflect the degrees of tubulointerstitial injury, using serum 1,25-dihydroxyvitamin D level as an index.