Association of an insulin gene promoter insertion polymorphism with type 2 diabetes and diabetic nephropathy in African Americans.

An insertion in the insulin gene promoter region among African American individuals was reported previously to reduce transcription. We typed two African American populations to determine the role of this variant. We identified the insertion in 5/260 diabetic cases and 1/135 matched controls from Arkansas (p=0.7), and 7/200 African American diabetic individuals and 5/198 matched controls from North Carolina (p=1.0). When all available data were pooled, the insertion was present in 1.66% of cases and 0.84% of controls (p=0.12; OR=2.0). By meta-analysis, the insertion was significantly associated with type 2 diabetes (OR=2.56; p=0.048), thus supporting a minor role in type 2 diabetes susceptibility.