Insulin secretion and computed tomography values of the pancreas in the early stage of the development of diabetes

Aims/Introduction: The computed tomography (CT) value of the pancreas was examined across the range of glucose tolerance, and the relationships between pancreatic CT values and factors responsible for glucose intolerance were analyzed. Materials and Methods: A total of 167 health-check examinees were classified into normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and diabetes mellitus (DM) according to 75 g oral glucose tolerance test (OGTT). Pancreatic and hepatic CT values were estimated at decreasing stages of glucose tolerance. The association of CT values of the pancreas and the indices of glucose tolerance were analyzed. Results: Insulinogenic index (II) was decreased from NGT through IGT to DM. Mean pancreatic CT value was decreased significantly from NGT through IGT to DM. Mean area under the curves of glucose (AUC-G) was significantly associated with II and insulin sensitivity index (ISI) composite in univariate analysis. In multiple regression analysis, II was most strongly inversely correlated with mean AUC-G, suggesting that II is the strongest determinant of glucose tolerance in Japanese. In addition, II was significantly associated with mean pancreatic CT value in univariate analysis. In multiple regression analysis, mean pancreatic CT value was strongly correlated with II. Conclusions: Pancreatic CT values were significantly decreased from NGT through IGT to DM. II was the strongest determinant of glucose tolerance, and was significantly influenced by pancreatic CT values. Thus, pancreatic fat deposition might impair insulin secretion in the early stage of development of type 2 diabetes, before overt deterioration of glucose tolerance. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00212.x, 2012)