Patients with type 2 diabetes who have poor glucose control face a significantly increased risk of fracture, despite high bone mineral density (BMD), researchers from The Netherlands report.
"Our findings reinforce the need of reevaluating the assessment of bone health in individuals with type 2 diabetes, particularly if their disease is not adequately controlled," Dr Fernando Rivadeneira from Erasmus Medical Center in Rotterdam told Reuters Health.
"Our findings further suggest that a more detailed indicator of glucose control (like Hb1AC measurements), instead of just 'presence or absence' of diabetes, may be needed for accurate fracture risk assessment," he said in an email.
Dr Rivadeneira and colleagues used data from The Rotterdam Study to investigate whether the relationship between BMD, bone geometry, and fractures in type 2 diabetes is influenced by glucose control.
How the study was done
Their study, published in Diabetes Care, included 3 715 patients without diabetes, 203 with adequately controlled diabetes (serum HbA1C below 7.5%), and 217 with inadequately controlled diabetes (serum HbA1C 7.5% or higher).
Participants with diabetes had higher BMD than those without diabetes at the lumbar spine and femoral neck, and among diabetics, BMD was higher in those with inadequately controlled disease than in those with adequate control.
Patients with inadequate control had the thickest bone cortices of all three groups, but there were no significant differences in bending strength among the comparison groups.
Despite these findings, individuals with inadequately controlled diabetes had a 62% higher fracture risk than did patients with adequate control and a 47% higher fracture risk than did individuals without diabetes. The fracture risk did not differ significantly between patients without diabetes and those with adequately controlled diabetes.
Findings in the study
These analyses suggest that patients with inadequate glucose control tend to experience fractures at a higher BMD than when the diabetes is well controlled, the researchers say.
The link between inadequately controlled disease and fracture risk, BMD and bone geometry remained after adjusting for various confounders, including the use of insulin and other antidiabetic medications.
"Assessing bone health should be an integral part of monitoring diabetic patients, since they are at risk of fracture even without a diagnosis of osteoporosis or even osteopenia," Dr Rivadeneira said.
"Further, the lack of any form of 'physiological bone loss' in the form of sustained high bone mineral density in type 2 diabetic patients may actually reflect a skeletal complication of inadequately controlled glucose metabolism."
He added that, "One of the next steps is looking prospectively at the patterns of change across longitudinal BMD measurements and markers of bone resorption in relation to glucose control (since our study focused on baseline BMD measurements)."
What the experts say
Dr Meryl S. LeBoff, who was not involved in the new research, said the higher risk of fracture seen in type 2 diabetes is likely multi-factorial.
"Although long-term studies are needed, these data indicate that good glycemic control may potentially emerge as a clinical approach to reduce fracture risk in adults with type 2 diabetes mellitus," Dr. LeBoff, director of the Skeletal Health and Osteoporosis Center and the Bone Density Unit at Brigham and Women's Hospital in Boston, told Reuters Health by email.
"While absolute bone density and some measures of hip structural measures are higher in adults with diabetes, data from the large Women's Health Initiative show that compared with non-diabetic women, women with insulin-treated type 2 diabetes mellitus have a lower bone density and bone strength measures relative to the lean body mass and loads on their skeleton," she noted.
(Will Boggs MD, Reuters Health, January 2013)
Diabetes and stress
Vitamin D may prevent fractures in older women