Continuous glucose monitors could provide benefits beyond helping people manage their blood sugar, according to a large study published in JAMA Network Open.
Researchers from Kaiser Permanente examined whether sustained use of continuous glucose monitoring (CGM) was associated with better long-term glucose control and kidney health in adults with type 2 diabetes.
The study included 25,648 adults considered at higher risk because they had poorly controlled diabetes or a history of severe hypoglycaemia.
Of these, 2,771 started using real-time CGM, while 22,877 served as a comparison group.
Researchers followed outcomes for up to three years.
What happened to HbA1c?
The differences in glucose control appeared relatively quickly and persisted.
After one year, HbA1c was approximately 1.1 percentage points lower in the CGM group than in the comparison group.
After three years, the difference remained substantial.
Average HbA1c was 7.83% in the CGM group, compared with 8.58% among non-users.
That represents a difference of approximately 0.75 percentage points, equivalent to around 8 mmol/mol.
The findings suggest that people who continue using CGM may be better able to maintain improvements in glucose management rather than experiencing a gradual deterioration over time.
What about kidney health?
Researchers also examined two important markers of diabetic kidney disease.
The first was the urinary albumin-to-creatinine ratio, or UACR, which measures how much albumin is leaking into the urine.
The second was estimated glomerular filtration rate, or eGFR, which assesses how effectively the kidneys filter blood.
After three years, UACR was approximately 125mg/g lower among people who continued using CGM than among those in the comparison group.
However, there was no significant difference in eGFR.
That distinction matters.
Lower albuminuria may indicate an improvement in kidney health, but the study did not establish that CGM prevents kidney failure or permanently preserves kidney function.
Why might CGM help?
CGM provides frequent glucose measurements throughout the day and night.
Unlike intermittent finger-prick blood glucose testing, it can show patterns and trends that may otherwise be missed.
This can help people understand how meals, physical activity, medication and illness affect glucose.
It may also provide earlier warnings of hypoglycaemia.
Over time, better glucose management could help reduce exposure to persistently high blood sugar, an important contributor to long-term complications.
What are the limitations?
This was not a randomised clinical trial.
Researchers used healthcare records and statistical techniques to approximate a trial comparing sustained CGM use with non-use.
People who continued using CGM may have differed from non-users in other important ways.
There was also substantial loss of participants from the analysis over time, including people who stopped using their sensors.
These factors mean the results demonstrate an association rather than proving that CGM caused the improvements.
What does this mean for the UK?
CGM is already an important part of diabetes management, particularly for people with type 1 diabetes and some people with insulin-treated type 2 diabetes.
The findings strengthen the case for studying its longer-term benefits among adults with type 2 diabetes who have difficulty maintaining glucose control.
But NHS eligibility and prescribing arrangements have not changed because of this study.
People with diabetes should continue attending their annual diabetes health checks, including kidney assessments.
Managing high blood pressure also remains essential for protecting kidney and cardiovascular health.
The important finding is that sustained glucose monitoring was associated with benefits lasting several years, although whether those benefits ultimately prevent serious kidney complications requires further research.
Primary study: Continuous Glucose Monitoring and Long-Term Glycemic and Kidney Outcomes – JAMA Network Open