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 reported, 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."