INS and obesity due to melanocortin 4 receptor deficiency: Vitamin D deficiency has been implicated in the progression and pathogenesis of diabetes.12, 13, 14, 15, 38 Vitamin D levels are also correlated with metabolic syndrome, obesity, insulin resistance, and cardiovascular disease.12, 13, 14, 15, 38 Vitamin D deficiency potentially may impact the development of diabetic retinopathy in several ways, such as affecting insulin secretion, insulin sensitivity, influencing inflammation, immunosuppression, microvascular and macrovascular events, and angiogeneisis.16, 17, 39, 40, 41, 42, 43