Women with type 1 diabetes have low bone density

Bone mineral density (BMD) in premenopausal women with type1 diabetes, also referred to as juvenile, diabetes, is 3 percent to 8 percent lower than in women without diabetes, investigators at the University of Pittsburgh report.

Studies have found that older women with type 1 diabetes have a greater risk of bone fracture compared with non-diabetic women. "We hypothesized that this may be due to lower BMD at an earlier age in women with type 1 diabetes," said lead investigator Dr. Elsa S. Strotmeyer.

"Additionally," she noted, "there is some suggestion from elderly populations that cardiovascular disease may be related to lower BMD, and cardiovascular disease is a common complication of type 1 diabetes."

To test their theory, Strotmeyer and her associates compared the fracture history and BMD of 67 women with type 1 diabetes, between 35 and 55 years old, with the fracture history of 237 nondiabetic women matched for the same ethnicity, age and socioeconomic status.

Compared with the nondiabetics, diabetic women had lower BMD at various sites, including bones in the hip, thigh, heel and whole body, Strotmeyer noted.

The team reports in the February issue of Diabetes Care that the diabetic women were also significantly more likely to report having a bone fracture after age 20 (33.3 percent versus 22.6 percent).

"It is not currently known why type 1 diabetes affects bone," Strotmeyer said, although "there are many possible theories."

It's possible that poor blood sugar control and increased bone turnover may be involved, she suggested. Also, it is likely that undetected "changes in the cardiovascular system, kidney or nervous system in type 1 diabetes, which are often associated with a longer duration of disease, are influencing bone."

Although the study did not evaluate these early or asymptomatic diabetes complications, "this is a future area for research."

The fact that women with type 1 diabetes already had lower BMD before menopause suggests that they may be at substantially increased risk of developing osteoporosis after menopause, Strotmeyer and her team point out.

They therefore recommend that "type 1 diabetic women should be targeted for osteoporosis screening and possible fracture prevention as they transition through menopause."

SOURCE: Diabetes Care, February 2006.