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Jump to Key Points MILAN — People with type 1 diabetes (T1D) are at nearly twice the risk of developing demyelinating diseases, including multiple sclerosis (MS), than those without diabetes, new research suggested.
In addition, the findings from two large US databases showed that the incidence of demyelinating diseases was higher in women with T1D than in men with T1D.
“This doubles down on the need to strengthen the monitoring of T1D patients for demyelinating diseases, particularly in females,” said Mathieu Lamy, MS, a pharmacoepidemiologist at Sanofi, speaking at the European Association for the Study of Diabetes (EASD) 2026 Annual Meeting.
Previous studies have linked T1D to other autoimmune diseases including MS, but this is believed to be the first study to both examine the association across all ages and for other non-MS demyelinating diseases, Lamy noted.
- T1D associated with ↑ demyelinating disease risk; adjusted IRR ~1.8.
- MS risk also ↑ in T1D: adjusted IRR 1.71-1.74.
- Women with T1D had higher demyelinating disease incidence than men.
- Other CNS demyelinating diseases also occurred more often in T1D.
- Vigilance for fatigue/tingling in T1D may improve recognition of demyelination.
A Retrospective Observational Study
The retrospective observational study used data from two large independent US databases, MarketScan Commercial and Medicare claims for the period 2016-2023, and TriNetX Dataworks electronic health records for 2017-2024. In MarketScan, a total of 84,704 individuals with T1D were matched with the same number of people without diabetes or prior demyelinating diseases seen in the same calendar year, whereas in TriNetX, a total of 176,100 individuals in each group were matched and compared. The mean age in both groups was about 36 years, with about equal numbers of men and women.
The overall incidence of demyelinating diseases per 100,000 patient-years in MarketScan was 81.55 among those with T1D vs 56.29 among those without diabetes, yielding a significant adjusted incidence rate ratio (IRR) of 1.76.
In TriNetX, the difference was also significant — 77.54 among those with T1D vs 42.61 among those without diabetes — yielding an adjusted IRR of 1.86 and “showing almost twice the risk of developing demyelinating disease once you already have type 1 diabetes,” Lamy said.
Similar findings were seen by subgroups. MS had an adjusted IRR of 1.71 in MarketScan and 1.74 in TriNetX. For other acute disseminated demyelination diseases, the IRRs were 0 and 1.81 in MarketScan and TriNetX, respectively, and for other demyelinating diseases of the central nervous system, the IRRs were 1.78 and 2.17 in MarketScan and TriNetX, respectively. All the differences were significant except for other acute disseminated demyelinating diseases, but that total number of events was small, Lamy noted.
Sex-specific analysis showed that women were at a significantly greater risk for all demyelinating diseases (110.37 vs 56.28 per 100,000 patient-years in MarketScan and 98.23 vs 56.24 per 100,000 patient-years in TriNetX) and specifically for MS (73.52 vs 33.75 per 100,000 patient-years in MarketScan and 68.02 vs 32.88 per 100,000 patient-years in TriNetX). “This is seen in the nondiabetic population and as well in the T1D population,” Lamy pointed out.
Clinicians Need to Be More Aware
After the presentation, an audience member from Slovenia commented, “I congratulate you for this study, because I think in clinical practice, we are not so vigilant about this disease. I’ve had several patients who complain about constant fatigue. This can be common in people with type 1 diabetes. One should really be attentive to MS and similar diseases, so thank you very much for making us alert.”
Another audience member, İlhan Satman, MD, professor emerita of internal medicine and endocrinology in the Istanbul Faculty of Medicine at Istanbul University in Istanbul, Turkey, told Medscape Medical News, “Today, MS and other demyelinating diseases are increasing. As one of the audience members said, I see many, many T1D patients complaining about fatigue. We used to think they were depressed and would send them to the liaison psychiatry clinic…. I think this really needs to be investigated…. We need to be more aware about this, and we need to listen to patients and not dismiss fatigue and tingling.”
Lamy is an employee of Sanofi, who funded the study. Satman reported no disclosures.
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 diaTribe. She is on X @MiriamETucker and Bluesky @miriametucker.bsky.social.
