TSH testing patterns similar between GLP-1 RAs, SGLT-2 inhibitors in diabetes patients on levothyroxine

Patterns of thyroid-stimulating hormone (TSH) test show no substantial difference between type 2 diabetes patients treated with GLP-1 RAs and those who received SGLT-2 inhibitors, a study has found.

A team of investigators conducted a retrospective cohort study emulating a target trial using Medicare from 1 January 2011 to 31 December 2020, with the primary analysis following an intention-to-treat approach. They matched patients via propensity scores and used logistic regression models.

Older adults aged ≥65 years with type 2 diabetes on a stable levothyroxine dose at baseline were identified. Participants initiated GLP-1 RAs or started/continued using SGLT-2 inhibitors. TSH testing during follow-up was the main outcome measure.

“In patients taking levothyroxine, weight loss can reduce thyroid hormone requirements and potentially associated adverse effects,” the investigators said.

Of the 5,370 matched patients (mean age 73.2 years), 71.6 percent were women, and 87.1 percent were White participants. Most patients (83.0 percent) in both treatment groups underwent TSH testing within 1 year of follow-up. The mean time to TSH testing was approximately 130.5 days for both groups.

“TSH testing patterns did not differ between GLP-1 RAs and SGLT-2 inhibitors, despite the greater likelihood of requiring levothyroxine dose adjustment associated with weight loss seen with GLP-1 RA therapy,” the investigators said.

“Given levothyroxine's widespread use, this gap suggests missed opportunities for timely and weight-responsive thyroid monitoring,” they added.