Beta cell function declines with age in glucose tolerant Caucasians.
OBJECTIVE
As type 2 diabetes results from an imbalance between insulin sensitivity and beta cell function, either or both may worsen with age. However, existing data are controversial on the effect of ageing on both insulin sensitivity and beta cell function.


METHODS
We enrolled 149 healthy, glucose tolerant and normotensive Caucasians (age 35 +/- 1 years, body mass index 26.07 +/- 0.44 kg/m2, waist-hip ratio 0.842 +/- 0.009 cm/cm, mean +/- standard error). A cross-sectional study was designed to examine the impact of age on insulin sensitivity and beta cell function. Their beta cell function (percentage B [%B]) and insulin sensitivity (percentage S [%S]) were estimated using the homeostasis model assessment.


RESULTS
Simple regression analysis revealed that %B declined with age (P = 0.008) while no relation was found between %S and age (P = 0.769). A stepwise regression analysis revealed that body mass index and diastolic blood pressure explained 14.7% of variation in %S, while age, waist-hip ratio, gender, and systolic blood pressure had no influence on %S. Age, body mass index and diastolic blood pressure together accounted for 21.7% of variation in %B, with age being an independent variable.


CONCLUSIONS
In the present study, we showed that beta cell function declined with age at a rate of about 1% per year. In contrast, insulin sensitivity was not affected by ageing. Our observations suggest that the age-related decline in glucose tolerance is primarily related to the loss of beta-cell function.
Chiu
K C
KC
Division of Endocrinology, Diabetes and Hypertension, University of California, Los Angeles, School of Medicine, Los Angeles, California, USA. kchiu@mednet.ucla.edu
Lee
N P
NP
Cohan
P
P
Chuang
L M
LM
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D001824:Body Constitution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D005947:Glucose / Q000502:physiology*; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000502:physiology*; D007515:Islets of Langerhans / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012737:Sex Factors
D007328:Insulin; D005947:Glucose