Table of Contents
December 22, 2025
4 min read
Key takeaways:
The prevalence of obesity is rising in veterans with type 1 diabetes.
Continuous glucose monitor use appears to reduce risk for mortality in veterans with type 1 diabetes.
Mortality rates are high in patients with type 1 diabetes, and overweight and obesity appear to be major factors, a speaker said during the World Congress on Insulin Resistance, Diabetes and Cardiovascular Disease.
Previous research has shown that among people diagnosed with type 1 diabetes by age 20, the estimated loss of life expectancy compared with people without type 1 diabetes is 11 years for men and 13 years for women, Peter D. Reaven, MD, staff physician and director of the diabetes program at Phoenix VA Health Care System and professor of clinical medicine at the University of Arizona College of Medicine, said during a presentation.
CGM use may lower mortality risk for veterans with type 1 diabetes, according to a target trial emulation approach with observational data. Image: Adobe Stock
Reaven discussed two studies his team conducted, one to examine the nature and patterns of excess weight in veterans and its relationship with cardiometabolic risk factors, and the other to determine whether continuous glucose monitoring can reduce mortality risk in veterans with type 1 diabetes.
Peter Reaven
“Mortality rates are still quite high in type 1 diabetes, and they are likely exacerbated by the rising prevalence of obesity and overweight,” Reaven said during the presentation. “While diabetes technologies are certainly helping our patients and may be associated with reducing mortality in these individuals, we clearly need to have a better understanding of what’s going on with weight gain in type 1 diabetes, and how we are going to manage this, as this is becoming an increasingly important problem.”
Excess weight and cardiometabolic risk
For the study on weight and cardiometabolic risk factors, Reaven and colleagues analyzed 9,712 veterans with type 1 diabetes (mean age, 54.6 years; 90% men; mean BMI, 28.1 kg/m2) appearing in a VA electronic health record database in 2022-23, of whom 2,726 had normal weight, 3,790 had overweight and 3,196 had obesity.
Patients with obesity were more likely to be on anti-obesity medication, antihypertensive medication, lipid-lowering medication and CGM than those from the other groups, but only 8% were on an anti-obesity medication, Reaven said.
In an analysis adjusted for age, sex and race/ethnicity, the prevalence of overweight or obesity was 72%, and in an analysis adjusted for sex and race/ethnicity, the prevalence of overweight or obesity was 68.6% in veterans aged 21 to 39 years, 77.5% in those aged 40 to 59 years and 68% in those aged 60 to 75 years, all of which are higher rates than seen in the general population, he said.
Between 2016 and 2023, the prevalence of obesity rose sharply in the youngest group, he said.
As weight category increased, blood pressure, triglycerides, LDL cholesterol and prevalence of metabolic syndrome rose, and estimated glomerular filtration rate and HDL cholesterol fell, Reaven said, noting that patients with obesity were more likely to have three or more cardiometabolic risk factors than patients from the other groups.
There is a J-shaped curve for total mortality and cardiovascular disease mortality by BMI, but when the sexes are separated, it is a U-shaped curve for men (P for interaction = .02), he said.
“There is a high and rising prevalence of obesity in our type 1 diabetes patients,” Reaven said during the presentation. “The rates are even worse in our VA population than what we have been seeing in the literature. It seems to be even more concerning in our younger type 1 diabetes patients. They are getting obesity earlier and they are going to be living with this longer. This excess weight appears associated with serious complications. Concerning is that anti-obesity medication use in this population is quite low. It’s an unmet issue and need.”
CGM and mortality risk
It is known that CGM metrics predict all-cause mortality in patients with type 1 and type 2 diabetes, and that initiation of CGM is associated with reduced risk for mortality in patients with type 2 diabetes, but there has never been a randomized controlled trial to determine whether CGM reduces risk for mortality in patients with type 1 diabetes, Reaven said during the presentation.
Reaven and colleagues used a target trial emulation approach with observational data on CGM use in veterans with type 1 diabetes “to try to align your inclusion and exclusion, risk factors and study design as closely as you can to a randomized clinical trial.” The second endocrinology visit in the VA system served as baseline “because that’s when CGM appeared to be initiated in more common fashion,” he said. “Instead of randomizing individuals to CGM or no CGM, [patients] were actually assigned in a nonrandomized fashion, and the randomization is emulated via cloning of the records to both groups. We start with all individuals in both groups simultaneously. Then we have a grace period of 6 months where you see whether they are assigned to a CGM or not. In each arm, the individuals are censored if they deviated from their assigned treatment pattern. Essentially, you are replicating a per-protocol randomized clinical trial effort.”
The cohort included 1,039 patients who received CGM and 7,399 who did not.
At 4 years, survival rates were higher in patients with CGM than in patients without it (log-rank P = .015) and weighting for covariates that predict CGM use did not change the results, Reaven said.
The CGM group had a 10% reduced risk for mortality compared with the non-CGM group at 1 year, and the difference grew to 16% at 4 years, he said.
The results did not change when the grace period was adjusted to 3 months or to 9 months, he said.
The benefit of CGM for reduced mortality risk was most prominent in patients aged 65 years or older and in patients not using an insulin pump, Reaven said.
The CGM group had numerically lower rates of hospitalization, hypoglycemia, hypo- or hyperglycemia and CVD at 4 years, but in the subgroup not on insulin pumps, the differences were statistically significant, he said.
“A target trial emulation with fairly robust causal inferences shows that CGM use appeared to be associated with reduced mortality. These curves begin to separate shortly after that 6-month grace period and continue to separate over time. The analysis was robust to many sensitivity analyses,” Reaven said.
Sources/Disclosures
Source:
Reaven P. Session 19 ⎯ Emerging topics in diabetes. Presented at: World Congress on Insulin Resistance, Diabetes and Cardiovascular Disease; Dec. 3-6, 2025; Los Angeles.
Reference:
Disclosures:
Reaven reports receiving grants from Dexcom and Eli Lilly.
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