Chronic diabetic complications are classified as microvascular or macrovascular and contribute to mortality and loss of quality of life. Hyperglycemia plays a critical role in the pathogenesis of microvascular complications, such as diabetic retinopathy, incipient nephropathy, and neuropathy, while atherosclerosis contributes to the pathogenesis of macrovascular complications. Diabetes mellitus and hypertension are frequently present together. Among many microvascular diabetic complications, hypertension plays a predominant role in the progression of diabetic nephropathy by glomerular hyperfiltration. Hypertension also induces atherosclerosis in diabetes. Thus, hypertension is a high-risk factor for both microvascular and macrovascular chronic diabetic complications. In this review, we summarize the current knowledge on the pathophysiological mechanisms of microvascular and macrovascular chronic diabetic complications with particular emphasis on the contribution of hypertension. We also briefly discuss various options available for the treatment of each diabetic complication.