CGM: 44% Lower Death Risk for Diabetics on Insulin

People with type 2 diabetes who use basal insulin and started wearing a continuous glucose monitor (CGM) had a 44 percent lower risk of death from any cause after one year, compared with those who did not wear a sensor. That is the finding of an analysis presented today, September 28, at the 62nd congress of the European Association for the Study of Diabetes (EASD) in Milan, which runs through October 2. The study was led by Prof. Jochen Seufert of University Hospital Freiburg, working with researchers from Abbott, maker of the FreeStyle Libre sensor, the device worn by nearly all CGM users in the analysis.

A CGM is a small sensor attached to the skin that measures glucose levels and sends the readings to a mobile phone, a dedicated reader, or an automated insulin delivery system. The technology has already been shown to improve blood sugar control and reduce episodes of dangerously low blood sugar in both type 1 and type 2 diabetes. Its role in reducing long term complications in type 2 patients on basal insulin had not been clear until now, and the researchers say this is the first analysis to link CGM use with a lower risk of death in that patient group.

What the analysis found

Researchers used the Truveta platform, a database of anonymized electronic health records covering more than 140 million people in the United States. They compared 13,935 adult patients who filled a CGM prescription for the first time with an equal number of patients who did not use a sensor, over the period from January 1, 2017, to March 18, 2024. The two groups were matched on 29 characteristics at the start of follow up, including age, sex, duration of diabetes, HbA1c level, and frequency of health care use, to reduce the influence of other differences. Participants’ average age was 58, and 47 percent were women.

Results after 12 and 24 months of follow up:

• death from any cause: 1.16 percent of CGM users versus 2.09 percent of those without a sensor after one year; 2.12 percent versus 3.26 percent after two years
• new cardiovascular events (heart attack, heart failure, stroke or transient ischemic attack, peripheral artery disease): 26 percent less frequent after one year and 24 percent less frequent after two years
• recurrent cardiovascular events: 35 percent less frequent after one year and 36 percent less frequent after two years
• hospitalization for heart failure: 54 percent less frequent after one year and 47 percent less frequent after two years

The findings held up even when the covid pandemic period and deaths within the first 90 days of follow up were excluded from the analysis.

Sources differ slightly on the exact percentage reduction in death risk. The EASD congress’s own press release cites 44 percent after one year and 35 percent after two years, while Abbott’s press release, from a company that took part in the study, cites 45 percent and 36 percent. The methodology and the database are the same in both releases; only the published percentage differs.

“Our study suggests that CGM can make a real difference for the long term health of people with type 2 diabetes who need insulin, and that it can help reduce the risk of premature death,” said Prof. Jochen Seufert, the study’s lead researcher from University Hospital Freiburg, in a statement for the EASD congress.

At the same congress, Abbott also presented a French study by the Guerci research team, conducted on more than 253,000 people with type 2 diabetes. It found that hospital admissions for acute diabetes complications, such as severe hyperglycemia, hypoglycemia, and diabetic coma, were 81 percent lower among patients not using insulin, 56 percent lower among those on multiple daily insulin doses, and 47 percent lower among those on basal insulin, in all cases among patients using Libre sensors.

“The observed association between CGM use and a lower risk of death and cardiovascular complications is significant, because it involves some of the most serious long term consequences of diabetes,” said Dr. Carol Wysham, an endocrinologist and clinical professor of medicine at the University of Washington School of Medicine, in Abbott’s press release.

What the study does not prove

The authors stress that this is an observational study, which cannot establish what exactly caused the lower rates of death and cardiovascular complications among CGM users. Despite matching on 29 characteristics, the influence of unmeasured factors cannot be ruled out, such as changes in therapy during follow up that the researchers did not specifically analyze. The sample may also not be representative of all adults with type 2 diabetes on basal insulin. The researchers themselves say larger prospective studies are needed to confirm the findings, since an association between sensor use and lower death risk, however strong, does not by itself prove that the sensor reduces the risk of death.