Comparison of the relationship of age and beta cell function in three ethnic groups.
METHODS
Prevalence of type 2 diabetes and glucose intolerance increase with age. It has been demonstrated that beta cell function declines at about 1% per year in glucose tolerant Caucasians. However, this relationship is not known to exist in other ethnic groups.


METHODS
We investigated the relationship of age to beta cell function (%B) and insulin sensitivity (%S), estimated by the homeostasis model assessment, in a nationally representative sample of healthy US adults who participated in a cross-sectional study, the third National Health and Nutrition Examination Survey. Only those subjects who had never been told to have diabetes by a physician, with HbA1C < 6% and fasting plasma glucose concentration < 5.56 mmol/l with proper fasting glucose and insulin concentration were included in this analysis (560 non-Hispanic whites, 231 non-Hispanic blacks and 298 Hispanics).


RESULTS
Age was positively correlated to HbA1C and fasting glucose concentration, but it was negatively correlated to %B in all three ethnic groups. In contrast, ageing had no influence on %S in all three ethnic groups. Pair-wise comparison showed age had a similar influence among three ethnic groups on fasting glucose concentration, HbA1C and %B, respectively. Multivariate analysis confirmed an independent influence of age on fasting glucose concentration, HbA1C and %B among three ethnic groups.


CONCLUSIONS
We observed %B declines at about 1% per year among all three ethnic groups. The age-related rising fasting plasma glucose concentration and HbA1C is most likely a consequence of age-related decline in beta cell function.
Chiu
Ken C
KC
Division of Clinical Epidemiology and Preventive Medicine, Department of Medicine, University of California and David Geffen School of Medicine, Los Angeles, California, USA. kchiu@mednet.ucla.edu
Martinez
Dorothy S
DS
Chu
Audrey
A
D000328:Adult; D001741:Black or African American; D000375:Aging / Q000097:blood / Q000208:ethnology* / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005215:Fasting / Q000097:blood; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006630:Hispanic or Latino; D006801:Humans; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000502:physiology*; D008297:Male; D008875:Middle Aged
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin