In aggregate, the percentage of glucagon-positive cells (the sum of PC1/3-positive and PC1/3-negative alpha cells), was significantly increased in donors with both type 1 diabetes and type 2 diabetes (35.52% vs 75.11% vs 57.53 for non-diabetic donors vs donors with short-duration type 1 diabetes vs type 2 diabetes, respectively) (Fig. 5f). This evidence concerns the gene GCG and type 2 diabetes mellitus.