Greater BMD Loss Seen in Men With Diabetes

Posted Oct 10, 2008.By Jeff Evans

MONTREAL (EGMN) - Loss of bone mineral density over time appears to be more severe in older men with type 2 diabetes than in older men without diabetes, even though men with diabetes have higher average bone mineral density at baseline, according to 4 years of follow-up data from a prospective study.

Fractures are more likely to occur in older adults with type 2 diabetes than in euglycemic older adults, even though studies have reported that those with type 2 diabetes have 4%-5% higher bone mineral density after adjustment for total lean and fat mass. Higher bone loss has been especially noted in older white women with diabetes, especially in those using thiazolidinediones (TZDs), Elsa S. Strotmeyer, Ph.D., said at the annual meeting of the American Society for Bone and Mineral Research.

Dr. Strotmeyer and her associates based their investigation on men in the Osteoporotic Fractures in Men (MrOS) study, which involved osteoporosis screening initially in 2000-2002 and a follow-up exam 4 years later of 5,995 ambulatory, community-dwelling men older than 65 years. The researchers examined dual x-ray absorptiometry exams from 4,094 of these men with a mean age of 73 years. Most of them were white (91%), and some had type 2 diabetes (14%) or impaired fasting glucose (IFG, 37%).

Men with diabetes had higher mean bone mineral density at baseline (0.986 g/cm²) than did men with IFG (0.963 g/cm²) or normal fasting glucose (0.947 g/cm²). At the end of the follow-up period, men with diabetes still had a greater mean level of bone mineral density (BMD) at the femoral neck than did the other men. But during the study period, men with diabetes lost a significantly greater mean amount of lean mass (2.8 kg) than men with either IFG (1 kg) or normoglycemia (gain of 1.5 kg). At follow-up, there were no differences in fat mass between the groups, said Dr. Strotmeyer of the Center for Aging and Population Health in the department of epidemiology at the University of Pittsburgh.

Despite their greater overall mean BMD, men with diabetes experienced a significantly greater annual decline in BMD at the femoral neck than did the other men. This yearly decrease (-0.562%) occurred at nearly twice the rate seen in men with IFG (-0.313%) or normal fasting glucose (-0.325%). This analysis was adjusted for body composition measures, total fat and lean mass, changes in fat and lean mass, demographics, lifestyle factors, medication and supplement use, and comorbidities.

At the end of follow-up, the bone area of men with diabetes had increased significantly more than in the other men. The men with diabetes also showed a greater loss of bone mineral content, although there was not a statistically significant difference among the groups. This meant that men with diabetes who had the lowest bone area at baseline actually had the greatest gain in bone area during the study. These were the men who not only lost the most BMD but also had less initial BMD at baseline, Dr. Strotmeyer said.

Although the percentage of BMD lost each year was significantly greater among men with diabetes who used TZDs than in other men, TZD use did not account for the loss of BMD in men with diabetes overall.

The investigators determined the men's diabetic status through self-report of a prior diabetes diagnosis, the use of hyperglycemic medications, or a high fasting glucose level. Impaired fasting glucose was defined through the American Diabetes Association criterion of a fasting glucose level of 100 mg/dL or greater, but less than 126 mg/dL.

The study received funding from several institutes in the National Institutes of Health.