INS and peripheral arterial disease: There are bodies of evidence showing that adequate status of vitamin D can modulate insulin sensitivity, immune and inflammatory responses, improve endothelial dysfunction and cardiometabolic health parameters [22–24], and vitamin D deficiency was associated with diabetes and its micro- and macrovascular complications such as DPN, diabetic nephropathy (DN), diabetic retinopathy (DR), peripheral arterial disease (PAD), cerebral infarction, and cardiovascular disease and risk factors, such as hypertension, dyslipidemia, and obesity [25–28].