Tricyclics May Up Fracture Risk in Type 2 Diabetes

VANCOUVER, BRITISH COLUMBIA — The use of tricyclic antidepressants (TCAs) conferred the highest risk for a new, first-time clinical fracture in people with type 2 diabetes with overweight or obesity, independent of any prevalent neuropathy, according to findings from an analysis of a large, randomized clinical trial.

Although the findings are suggestive, they don’t definitively pin blame on TCAs, said Rachel Elam, MD, who presented the study at the American Society for Bone and Mineral Research (ASBMR) 2023 Annual Meeting. "I think that there's not enough information to conclude that tricyclic antidepressants directly lead to fractures, but I think it opens the door [to] something we should look into more. Is it being mediated by a better predictor, or is it the medication itself? I think it's more hypothesis generating," said Elam, an assistant professor of medicine in the division of rheumatology at the Medical College of Georgia at Augusta University.

Patients with type 2 diabetes are known to be at increased risk of fracture, but prediction tools tend to underestimate this risk, Elam said. "Type 2 diabetes specific clinical risk factors may be helpful for finding out fracture risk in this population," Elam said during her talk.

Glycemic control is one candidate risk factor because advanced glycation end products are linked to reduced bone strength. Other factors include antidiabetic medication use, neuropathy, and microvascular disease, which has been linked to increased cortical porosity.

The study examined a somewhat younger population than previous surveys, having drawn from the Look AHEAD-C clinical trial, which examined the effects of an intensive lifestyle intervention on type 2 diabetes. Look AHEAD-C included 4697 participants aged 45-75 from 16 US clinical sites. Participants had a body mass index of 25.0 kg/m² or higher and HbA1c levels of 11% or below.

Elam cited the database’s inclusion of factors like A1c levels, renal parameters, and diabetic neuropathy. "It gave us a really good population to look at those risk factors" in a large group of people with type 2 diabetes, she said.

Over a median follow-up of 16.6 years, there were 649 participants with incident first clinical fracture(s). Statistically significant factors predicting fracture risk included TCA use (hazard ratio [HR], 2.24; 95% CI, 1.14-4.43), female gender (HR, 2.20; 95% CI, 1.83-2.66), insulin use (HR, 1.26; 95% CI, 1.02-1.57), increases in HbA1c level (per 1% increase: HR, 1.12; 95% CI, 1.04-1.20), age (HR, 1.02; 95% CI, 1.01-1.04), other or mixed race/ethnicity (HR, 0.68; 95% CI, 0.52-0.87), Hispanic White race/ethnicity (HR, 0.60; 95% CI, 0.39-0.91), non-Hispanic Black race/ethnicity (HR, 0.35; 95% CI, 0.26-0.47), and estrogen use (HR, 0.65; 95% CI, 0.44-0.98).

During the Q&A session following the presentation, Elsa Strotmeyer, PhD, commented that TCAs have been linked to central nervous system pathways in falls in other populations. "It’s a very nice study. It's important to look at the diabetes complications related to the fracture risk, but I thought that they should have emphasized some more of the diabetes complications being related to fracture rather than these tricyclic antidepressants, because that is not a unique factor to that population," said Strotmeyer, who is an associate professor of epidemiology at the University of Pittsburgh, Pittsburgh, Pennsylvania.

Instead, she noted a different strength of the study. "The study population is important because they're a relatively young population with type 2 diabetes, compared to many studies [that] have been published in older populations. Showing similar things that we found in older populations was the unique piece and the important piece of this study," Strotmeyer said.

Ultimately, the model wasn’t sufficient to be used as a fall risk predictor, but it should inform future work, according to Elam. "I think it does lay some new groundwork that when we're looking forward, it may [help in building] other models to better predict fracture risk in type 2 diabetes. Things that would be important to include [in future models] would be medication use, such as tricyclic antidepressants," and to make sure we include glycemic control, hemoglobin A1c, and insulin medication.

The study was independently funded. Elam and Strotmeyer report no relevant financial relationships.

American Society for Bone and Mineral Research (ASBMR) 2023 Annual Meeting: Abstract 1026. Presented October 14, 2023.

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Cite this: Tricyclics May Up Fracture Risk in Type 2 Diabetes - Medscape - Oct 17, 2023.