Glycemic control, disease duration predict fracture risk in type 1 diabetes
Long disease duration and an HbA1c of at least 7.9% are independent risk factors for sustaining multiple fractures among adults with type 1 diabetes, according to findings from a cross-sectional analysis published in Bone.
“While risk factors for fractures in [type 2 diabetes] have been characterized, risk factors for fractures in [type 1 diabetes] have not yet been fully elucidated,” Nicola Napoli, MD, PhD, of the division of endocrinology and diabetes at the University Campus Bio-Medico di Roma in Rome, and colleagues wrote in the study background. “Hypoinsulinemia, low levels of [insulin-like growth factor I] and vitamin D, poor metabolic control, vascular complications and lipid profile have all been studied as possible contributors to poor bone health in [type 1 diabetes], with controversial results. The majority of available clinical studies in this regard are limited in the number of subjects or by the lack of information about crucial data such as metabolic control, insulin exposure or hypoglycemic events.”
Napoli and colleagues analyzed data from 600 adults with type 1 diabetes attending one of three outpatient clinics in Rome with 5 years of follow-up data and no history of secondary causes of osteoporosis or use of drugs that affect bone metabolism (300 women; mean age, 42 years; mean BMI, 24.4 kg/m²; mean diabetes duration, 19.9 years). Low trauma, nonvertebral fracture incidence was evaluated via questionnaire and medical records. Researchers used multinomial logistic regression analyses to determine the contribution of explanatory variables to the occurrence of single and multiple fractures, with results adjusted for age, sex and BMI.
Within the cohort, 111 participants sustained at least one fracture (18.5%), with 29 of those patients reporting at least two fractures. Median age at first fracture was 37 years, and median age at second fracture was 41 years. The most common fracture sites reported were at the hand (18.6%), foot (17.1%) and tibia/fibula (10.5%). The 5-year average HbA1c was 7.6%, according to researchers.
Researchers found that HbA1c and disease duration persisted as independent risk factors for multiple fractures after adjustment. Participants in the highest tertile of HbA1c ( 7.9%) were 3.5 times more likely to experience multiple fractures vs. participants in the lowest HbA1c tertile (< 7.2%; RR = 3.5; 95% CI, 1.04-11.73). Similarly, participants in the highest tertile of disease duration ( 26 years) were 7.5 times more likely to sustain multiple fractures vs. those in the lowest disease duration tertile (< 14 years; RR = 7.59; 95% CI, 1.6-35.98).
In adjusted logistic regression models, researchers found each 1-U increase in creatinine clearance rate was associated with reduced risk for sustaining a single fracture (RR = 0.22; 95% CI, 0.06-0.83). The presence of neuropathy was associated with increased risk for a single fracture (RR = 2.57; 95% CI, 1.21-5.46) and multiple fractures (RR = 2.57; 95% CI, 0.92-7.15), according to researchers.
“To our knowledge, this is the first study assessing fracture risk factors in a subpopulation of multi-fractured [type 1 diabetes] patients,” the researchers wrote. “This allowed us to show that poor glycemic control over the previous 5 years and long disease duration are associated with increased risk of multiple fractures. Although an association between poor glycemic control and increased fracture risk has been reported for individuals with [type 2 diabetes], the evidence on glycemic control and fracture risk in [type 1 diabetes] is less consistent.”
The researchers noted that glycemic control and kidney function are modifiable risk factors that could be targeted for prevention of fractures in diabetes. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.