Diabetic Nephropathy: Which Risk Factor is Most Strongly Associated?

Some risk factors for diabetic nephropathy can't be modified, but they support aggressive treatment to control hyperglycemia.

Without intervention, approximately 30% of patients with type 2 diabetes will progress to overt diabetic nephropathy and, after 20 years of nephropathy, approximately 20% develop ESRD. Poor glycmemic control is a significant contributing factor.

Which of the following other risk factors demonstrates the strongest association with development of diabetic nephropathy?