Background: a better understanding of the vitamin-D system's physiological role, particularly its potential effects on inflammatory and autoimmune conditions, insulin secretion, and possibly also resistance to insulin, interest in its potential role in the prevention and control of diabetes, both type 1 and type 2, has grown. Both of these diseases are linked to inflammation, with type 1 diabetes also having an autoimmune component. Indeed, animal and human research suggest that appropriate vitamin D supplementation may reduce the prevalence of type 1, diabetic microvascular complication and perhaps type 2 diabetes mellitus, as well as enhance metabolic control in people with diabetes. Aims: Evaluation of the role of diabetes mellitus type 1 on the level of vitamin D3 and comparison between patients of diabetes with and without Nephropathy in Iraqi.