SGLT2 Inhibitors for Diabetes: No Link to Fractures in Older Adults

Use of sodium-glucose cotransporter-2 (SGLT2) inhibitors does not appear to raise the risk for fractures in older adults, new research suggests.

The data come from a nationwide propensity score-matched study of US Medicare recipients with type 2 diabetes who were new users of either an SGLT2 inhibitor, a dipeptidyl peptidase 4 (DPP-4) inhibitor, or a glucagon-like peptide (GLP-1) receptor agonist.

"The use of SGLT2 inhibitors was not associated with an increased risk of nontraumatic fractures compared with DPP-4 inhibitors or GLP-1 agonists. Results were consistent across categories of sex, frailty, age, and insulin use," say Min Zhuo, MD, of Harvard Medical School, Boston, Massachusetts, and colleagues, who published their work online October 27 in JAMA Network Open.

"Our results add to the evidence base evaluating the safety profile of SGLT2 inhibitors in older adults outside of [randomized controlled trials] and further characterize the risk-benefit balance of SGLT2 inhibitors in clinical practice," they write.

Asked to comment, Simeon I. Taylor, MD, PhD, told Medscape Medical News, "This is a high-quality study that is generally reassuring that relatively short, less than 1 year, treatment with an SGLT2 inhibitor does not appear to significantly increase the risk of bone fractures."

However, Taylor, of the Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, also noted: "Notwithstanding these reassuring data, the paper also does a good job of pointing out important limitations."

"Most importantly, these data do not address questions related to the risk of long-term chronic therapy. It is instructive to refer back to the published data demonstrating an approximately 2-year lag before a significant increase in the risk of fracture was observed in rosiglitazone-treated patients in the ADOPT study. The length of the lag is likely related to the baseline bone mineral density at the time drug therapy is initiated. These considerations may contribute to the observed variation in bone-related outcomes in different studies."

Concern about SGLT2 inhibitors and fractures first arose in 2017 from the CANVAS study, in which the overall fracture risk with canagliflozin was a significant 26% higher than placebo. However, subsequent larger randomized trials of canagliflozin and other SGLT2 inhibitors did not find the same risk.

In addition, previous observational studies in younger adults have also not found use of SGLT2 inhibitors to be associated with increased fracture risk compared with DPP-4 inhibitors or GLP-1 agonists.

Understanding Fracture Risk With SGLT2 Inhibitors Is "Critical"

Older adults with type 2 diabetes may benefit from reductions in atherosclerotic cardiovascular events, hospitalization for heart failure, end-stage kidney disease, and death associated with SGLT2 inhibitors, but the fact that aging may have negative effects on bone metabolism means "understanding the fracture risk associated with SGLT2 inhibitors in older adults with type 2 diabetes is critical," say Zhuo and colleagues.

In the current study, they analyzed claims data for Medicare beneficiaries aged 66 years and older (1 year past Medicare eligibility) who were newly prescribed an SGLT2 inhibitor, DPP-4 inhibitor, or GLP-1 agonist between April 1, 2013 and December 31, 2017.

A total of 45,889 patients from each treatment group were propensity-matched using 58 baseline characteristics, for a total of 137,667 patients.

After matching, there were 501 events of the primary composite outcome (nontraumatic pelvic fracture, hip fracture requiring surgery, or humerus, radius, or ulna fracture requiring intervention) within 30 days. By treatment group, fracture rates per 1000 person-years were 4.69, 5.26, and 4.71 for SGLT2 inhibitors, DPP-4 inhibitors, and GLP-1 agonists, respectively.

The differences between patients taking DPP-4 inhibitors or GLP-1 agonists compared with SGLT2 inhibitors were not significant, with hazard ratios of 0.90 and 1.00, respectively.

Results remained consistent in various sensitivity and subgroup analyses, including limiting the data to just the canagliflozin group. Overall, the fracture rate was greater with female sex, frailty, older age, and insulin use, consistent across drug classes.

The risks for falls and hypoglycemia were lower in the SGLT2 inhibitor versus matched DPP-4 inhibitor groups (hazard ratio [HR], 0.82), and there was no difference in syncope. None of those differences were significant for the SGLT2 inhibitor group compared with the GLP-1 agonist group.

Consistent with previous data, the risk for diabetic ketoacidosis was higher with SGLT2 inhibitors versus DPP-4 inhibitors and GLP-1 agonists (HR, 1.29 and 1.58), and the risk for heart failure hospitalization was lower (HR, 0.42 and 0.69).

The study was funded by the Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School. Zhuo was supported by the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases. Taylor is a consultant for Ionis Pharmaceuticals.

JAMA Netw Open. 2021;4:e2130762. Full text

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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