Insulin, glucagon and somatostatin stores in the pancreas of subjects with type-2 diabetes and their lean and obese non-diabetic controls

In type-2 diabetes, both insufficient insulin and excessive glucagon secretion contribute to hyperglycemia. We compared insulin, glucagon and somatostatin stores in pancreas obtained at autopsy of 20 lean and 19 obese non-diabetic (ND), and 18 type-2 diabetic (T2D) subjects. From concentrations and pancreas weight, total content of hormones was calculated. Insulin content was 35% lower in T2D than ND subjects (7.4 versus 11.3 mg), whereas glucagon content was similar (0.76 versus 0.81 mg). The higher ratio of glucagon/insulin contents in T2D was thus explained by the decrease in insulin. With increasing BMI of ND subjects, insulin and glucagon contents respectively tended to increase and decrease, resulting in a lower glucagon/insulin ratio in obesity. With aging, insulin and glucagon contents did not significantly change in ND subjects but declined in T2D subjects, without association with the duration of diabetes or type of treatment. The somatostatin content was lower in T2D than ND subjects (0.027 versus 0.038 mg), but ratios somatostatin/insulin and somatostatin/glucagon were not different. In conclusion, insulin stores are about 1/3 lower in T2D than ND subjects, whereas glucagon stores are unchanged. Abnormal secretion of each hormone in type-2 diabetes cannot be attributed to major alterations in their pancreatic reserves.