From Keio U: Islet number rather than islet size is a major determinant of beta and alpha cell mass in humans

J Clin Endocrinol Metab. 2014 Feb 11:jc20133731. [Epub ahead of print]

Islet number rather than islet size is a major determinant of beta and alpha cell mass in humans.

Kou K1, Saisho Y, Sato S, Yamada T, Itoh H.

Author information

• 1Department of Internal Medicine, Keio University School of Medicine.

Abstract

Objective: To clarify the relative contribution of islet number and islet size to beta and alpha cell mass in humans. 

Research Design and Methods: We obtained the pancreas at autopsy from 72 Japanese adults with no history of diabetes or pancreatitis (age 47 ± 12 years, BMI 24.1 ± 5.0). Pancreatic sections were stained for insulin or glucagon, and fractional beta cell area (%BCA) and alpha cell area (%ACA) were measured. Islet number and islet size as well as beta cell turnover were also quantified. HbA1c measured within 1 year prior to death was obtained in 38 individuals. 

Results: There was considerable inter-individual variation in islet density and mean islet size, with a significant negative correlation between the two (r = -0.25, P = 0.03). There were significant positive correlations between islet density and %BCA or %ACA (r = 0.63, P <0.001 and r = 0.41, P = 0.001), whereas mean islet size correlated with neither of them. Islet density as well as %BCA, but not mean islet size, was negatively correlated with HbA1c (r = -0.37, P = 0.02 and r = -0.36, P = 0.03). 

Conclusion: The present study suggests that islet number rather than islet size is a major determinant of beta and alpha cell mass in humans. Inter-individual difference in islet number may contribute to susceptibility to development of glucose intolerance.