Does hyperinsulinemia preserve bone?
OBJECTIVE
Obesity and NIDDM are each associated with increased bone mineral density (BMD). We therefore hypothesize that hyperinsulinemia is an osteogenic factor.


METHODS
Subjects consisted of 411 men and 559 women aged 50-89 years who were participants in the Rancho Bernardo Heart and Chronic Disease Study and were not diabetic by history or oral glucose tolerance test. Fasting and 2-h postchallenge insulin were measured by radioimmunoassay. Bone mineral density was measured at the midshaft radius with single photon absorptiometry and at the lumbar spine and hip with dual energy X-ray absorptiometry.


RESULTS
Multiple regression analyses indicated that among men, a significant insulin-BMD association at the hip was no longer apparent after adjusting for covariates. Among women, fasting insulin was significantly and positively associated with bone density of the radius and spine (P < 0.05), independent of age, BMI, waist-hip ratio, postmenopausal estrogen use, age at menopause, thiazide use, family history of diabetes, current cigarette smoking, and exercise. Each 10 microU/ml increase in fasting insulin was associated with an increase of 0.33 and 0.57 g/cm2 of the radius and spine, respectively.


CONCLUSIONS
Hyperinsulinemia may be responsible for part of the observed association of both diabetes and obesity with BMD in women.
Barrett-Connor
E
E
Department of Family and Preventive Medicine, University of California, San Diego, La Jolla 92093-0607, USA. ebarrettconnor@ucsd.edu
Kritz-Silverstein
D
D
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015519:Bone Density; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology; D005260:Female; D006801:Humans; D006946:Hyperinsulinism; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010012:Osteogenesis; D010384:Pelvic Bones; D011884:Radius; D012044:Regression Analysis; D012727:Sex Characteristics; D013131:Spine
D007328:Insulin