CGM can help patients see the effects of lifestyle changes in T2D: Thomas Martens, M.D. | ADA 2026

Participants in the CONNECT randomized controlled trial stayed on their existing non-insulin therapies, yet continuous glucose monitoring (CGM) still produced additive A1C benefits. Based on the study’s findings, the changes in A1C were driven by behaviorial changes, not medication, study co-author Thomas Martens, M.D., of HealthPartners, told Managed Healthcare Executive following the 2026 American Diabetes Association Scientific Sessions.

Participants could adjust their regimens over the 26-week study, intensifying or reducing therapy as they saw fit, so researchers examined what accounted for the between-group difference. It did not appear to be insulin addition, Martens said. There was a slight uptick in glucagon-like peptide-1 (GLP-1) use in the CGM arm relative to routine care, but much of the improvement was traced to lifestyle change. Because glucose responds to what people eat, how they exercise and other daily habits, CGM lets them see the immediate impact of those choices.

"If you can see it, you can change it," Martens said. And once patients could see what drove their glucose to rise, most seemingly acted on it. That visibility, he suggested, is simply how people learn.

The trial's five-hour-per-day improvement in time in range underscores that mechanism. Time in range measures the share of the day spent between 70 and 180 mg/dL, with consensus targets above 70% of the day, which loosely corresponds to an A1C near 7%, Martens said. Every 5% gain is associated with reduced complication risk.

He argued the metric is more actionable than A1C alone. Because A1C reflects roughly three months of averaged glucose, recent improvement is hard to detect, whereas time in range can reflect a lifestyle change within a week — and CGM studies often show gains in the first few weeks. Martens called the five-hour daily increase clinically meaningful: substantial added time in a safer glucose range.