(1)Objectives: The effect of vitamin D3 supplementation on markers of metabolic and inflammatory markers in patients with diabetic nephropathy. (2) Design: Randomized Double blind clinical Trial, with a sample size of 50 patients. (3) Setting and conduct: After the patients participating, were randomly divided into 2 groups. The first blood samples were taken from the subjects after assessing their anthropometric measurements and taking their 3day food record. Then, they were asked to consume either of the Vitamin D3 or placebo for 8 weeks. More so, they were asked not to change their regular diet, activity and medicine during the study. Second Blood samples were also taken after an overnight fasting and before-after analysis was performed finally. (4) including major eligibility criteria: (4-a) Major Inclusion Criteria: With type 2 diabetes, blood glucose less than 140 mg/dl, stage 3 and 4 diabetic nephropathy and albuminuria more than 30 mg/day, the lack of proof for vitamin D is more than 15 ng/l and less than 30 ng/l. (4-b) Major Exclusion Criteria: Calcium and vitamin D supplements during the study, more than 2.5 mg/dL phosphorus, calcium modified more than 10 mg/dl, taking magnesium antacids, thiazide diuretics consumption.(5) Intervention: Group 1 (Intervention group) who weekly received 1 pearl containing 50000 unit cholecalciferol supplements after the lunch meal, and Group 2 (Placebo group) who received placebo as the same, all for 8 weeks. (6) Main outcome measures (Variables): Albuminuria, Fasting blood sugar, Serum insulin, TNFα, Interlukin6, Hemoglobin A1c, Blood pressure