a person scanning blood glucose with a flash glucose monitor

Does a Glucose Monitor Help Without Insulin?

In an open-label 26-week trial, adults with type 2 diabetes not on insulin lowered HbA1c 0.9 percentage points more with a CGM; the device maker paid.

In a 26-week trial at 22 US primary care practices, adults with type 2 diabetes who were not taking insulin lowered HbA1c by 0.9 percentage points more with a continuous glucose monitor than with routine care — an open-label result that bundles the device with the coaching that comes with it.

Twenty-six weeks of continuous glucose monitoring lowered HbA1c by 0.9 percentage points more than routine care in 283 adults with type 2 diabetes not taking insulin at 22 US primary care practices, to 7.2% vs 8.0% (95% CI -1.1 to -0.6). The trial was open-label, so participants knew who could see their readings; the gain reflects the device plus its coaching. Dexcom, the manufacturer, funded it.

What this means

For adults with type 2 diabetes who do not use insulin and start above target, a sensor plus its coaching — the trial was open-label — produced a real but short-term improvement. This is not evidence that monitoring prevents complications, replaces medication, or outlasts the sensor. Cost is not addressed in what we could read.

What the trial found

The CONNECT trial assigned 283 people aged 21 to 84 in US primary care to a sensor or routine care. Baseline HbA1c averaged 8.8% with monitoring and 8.7% without. Time in range — the share of the day that glucose stays between 70 and 180 mg/dL — was 21 percentage points higher (95% CI 16 to 26), a sensor-measured secondary outcome, not a clinical endpoint. Neither group reported severe hypoglycemia. A 2021 trial in insulin-treated type 2 diabetes found 0.4 percentage points.

What it does not show

The trial was open-label, so onboarding and the nudge of watching glucose move sit inside that number — plausibly why it runs roughly twice the insulin-trial effect size. Durability past 26 weeks is untested; a separate six-week program found its early gains did not last. Everyone started near 8.8%, so this says nothing about people at target, type 1 diabetes or insulin users. Complications and medication reduction were not tested. Author disclosures sit behind the paywall; only the abstract was available to us at press time.

Terms explained

  • Continuous glucose monitoring (CGM) — a wearable sensor that measures glucose in tissue fluid every few minutes instead of fingerstick checks.
  • HbA1c — a blood test reflecting average glucose over two to three months.

Sources

  1. Oser TK, et al. Continuous Glucose Monitoring in Non-Insulin-Treated Type 2 Diabetes. The New England Journal of Medicine. Published Oct. 14, 2026. doi:10.1056/NEJMoa2608571 · PMID: 42878622
  2. Martens T, et al. Effect of Continuous Glucose Monitoring on Glycemic Control in Patients With Type 2 Diabetes Treated With Basal Insulin. JAMA. 2021. doi:10.1001/jama.2021.7444 · PMID: 34077499
  3. Zhang, et al. The Upfront Effectiveness of a 6-Week Continuous Glucose Monitoring Intervention for Non-Insulin-Using Individuals With Type 2 Diabetes Is No Longer Detectable at 6–12 Months: An Observational Follow-Up of a Randomized Trial Cohort. Diabetes Obes Metab. 2026. doi:10.1111/dom.71048 · PMID: 42381345 · full text verified, open access (PMC13538816), 2026-10-20

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