β-Cell Mass and Turnover in Humans: Effects of obesity and aging

OBJECTIVE: We sought to establish β-cell mass, β-cell apoptosis, and β-cell replication in humans in response to obesity and advanced age. RESEARCH DESIGN AND METHODS: We examined human autopsy pancreas from 167 nondiabetic individuals 20–102 years of age. The effect of obesity on β-cell mass was examined in 53 lean and 61 obese subjects, and the effect of aging was examined in 106 lean subjects. RESULTS: β-Cell mass is increased by ∼50% with obesity (from 0.8 to 1.2 g). With advanced aging, the exocrine pancreas undergoes atrophy but β-cell mass is remarkably preserved. There is minimal β-cell replication or apoptosis in lean humans throughout life with no detectable changes with obesity or advanced age. CONCLUSIONS: β-Cell mass in human obesity increases by ∼50% by an increase in β-cell number, the source of which is unknown. β-Cell mass is well preserved in humans with advanced aging.