Diabetes Predicts 10-Year Bone Fracture Risk

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Diabetes Predicts 10-Year Bone Fracture Risk
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Monday, Sept. 19, 2011 (MedPage Today) -- SAN DIEGO —
Diabetes is a significant predictor of fracture risk, independent of
conventional risk factors, Canadian researchers said here at the annual meeting
of the American Society for Bone and Mineral Research.


  After controlling for age, sex, osteoporosis medications, bone mineral density (BMD), and
other factors, diabetes was significantly associated with an increased risk of
major osteoporotic fracture during the subsequent ten years, Lora Giangregorio,
PhD, of the University of Waterloo in Ontario, reported.


  Recent studies have suggested a possible link between diabetes and elevated
fracture risk.
To explore this, Giangregorio's group analyzed data from a large database in
Manitoba that included 3,518 individuals with diabetes and 36,085 without
diabetes.
Fracture risk was calculated according to the World Health Organization's
FRAX tool, which rates risk according to a number of factors such as age, sex,
height and weight, smoking, glucocorticoid use, and personal or parental history
of hip fracture.
Diabetes is not currently included in the FRAX group of risk factors, she
pointed out.
The tool also can calculate an individual's probability of future fracture
as being low, with a risk below 10 percent; moderate, with a risk between 10
percent and 20 percent; and high, with a risk exceeding 20 percent.
At baseline, more of the diabetics were men. They also were older, had
higher BMIs, and were more likely to have chronic obstructive pulmonary
disease and to be taking glucocorticoid medications.
"Despite all these risk factors, fewer of those with diabetes were receiving
osteoporosis medications," Giangregorio said.
Mean probabilities of fracture before controlling for risk factors were
similar for diabetics and nondiabetics for major fractures and hip
fractures.
 However, after adjustment for clinical and FRAX risk factors, the FRAX
probability risk was higher among diabetics, the researchers reported.
On Kaplan-Meyer analysis, the ten-year probability of fracture was
significantly higher among the patients with diabetes, with a difference in the
fracture-free survival curves already evident early in the study and continuing
throughout.
 There also was a higher mortality risk among the diabetic group, which
"attenuated the risk for fracture, but did not eliminate it," she said.
There were no significant interactions between diabetes and age, sex, or
femoral neck BMD for major osteoporotic fracture.
However, a significant interaction was seen for age and diabetes on risk for
hip fracture, with diabetes being a stronger predictor for individuals younger
than 65.
 The number of fractures in the below-65 group was small, though, so this
interaction should be viewed cautiously, Giangregorio said.
 When they looked at concordance between the three levels of probability of
fracture, they found good concordance for the group without diabetes.
But in the group with diabetes the curves shifted upward, indicating that
FRAX underestimated risk for both major osteoporotic fracture and hip fracture,
she explained.
  "In future iterations of the FRAX tool, consideration might be given to
adding diabetes to the list of risk factors," she said.
In their analysis, the researchers did not distinguish between type 1 and
type 2 diabetes, which they acknowledged was a limitation of the study.

A second Canadian study presented in a poster session also found that
patients with diabetes were less likely than nondiabetics to receive treatment
with a bisphosphonate, even though they were more likely to have a history of
fracture.

In presenting her findings, lead author Lisa-Ann Fraser, MD, of the
University of Western Ontario-McMaster University in Ontario noted that both
type 1 and 2 diabetes were associated with fractures.

Type 1 diabetes is associated with changes in bone structure, which results
in a decrease in BMD and an increase in the associated risk factors, she
explained to MedPage Today. The mechanism in type 2 diabetes is less
clear, Fraser said.


 
          Last Updated: 09/20/2011