medwireNews: Poor glycemic control is associated with an increased risk for low-trauma fracture in people with type 1, but not type 2, diabetes, study findings indicate.
Using data from a UK-based primary care database, Christian Meier (University Hospital Basel, Switzerland) and colleagues showed that individuals with type 1 diabetes and a mean glycated hemoglobin (HbA1c) level above 8.0% had a significant 39% higher risk for non-vertebral fractures of the proximal and distal upper and lower extremities, ribs and thorax, hip, and foot than those with an HbA1c level at or below 7.0%.
Fractures occurred a median 4.5 years after diabetes onset but were not significantly increased among patients with an HbA1c level above 7.0% but below 8.0%, versus those with a level below 7.0%.
The findings, published in The Journal of Clinical Endocrinology & Metabolism, are based on medical records from 672 individuals with a low-trauma fracture after type 1 diabetes onset and 2657 controls with no fracture who were matched for a number of variables including age, sex, and diabetes type and duration.
For the 44,275 patients with type 2 diabetes, including 8859 with a fracture, there was no significant association between glycemic control and fracture risk.
Meier and co-investigators say that their findings “can be explained by the different pathophysiological mechanisms contributing to skeletal fragility in each [diabetes] type.”
For example, patients with type 1 diabetes experience rapid bone loss during the first few years after disease onset, whereas obesity-related insulin resistance during the early stages of type 2 diabetes has a protective effect on bone health. Indeed, “patients with [type 2 diabetes] usually present with a higher bone mass compared to healthy controls,” the researchers remark.
In their multivariate analyses, adjusted for covariates including BMI, smoking, diabetes complications, and medication type, the researchers observed a number of other factors significantly and independently associated with increased fracture risk.
For type 1 diabetes these included previous fracture, ischemic heart disease, chronic renal failure, diabetic retinopathy, previous falls, and use of pioglitazone and bisphosphonates, at hazard ratios ranging from 1.29 to 2.83.
For type 2 diabetes, being a current or ex-smoker, having previous fracture, chronic renal failure, diabetic retinopathy, previous falls, and decreased vision, as well as using insulin, pioglitazone, rosiglitazone, bisphosphonates, and calcium and other supplements, were all significantly associated with increased fracture risks, at hazard ratios of 1.10 to 1.75.
By Laura Cowen
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