New CGM Metrics May Catch Hidden Blood Sugar Dangers

What This Study Found

Researchers looked at CGM data from 30,000 people with Type 1 diabetes to test four new ways of measuring blood sugar patterns. They found that these new metrics — called rebound hyperglycemia, rebound hypoglycemia, extended hyperglycemia, and extended hypoglycemia — give extra information that standard CGM numbers alone don't always show. In particular, these new measures were especially good at spotting dangerous low blood sugar events linked to large glucose swings.

Why This Matters for You

If you wear a CGM, you're probably familiar with numbers like Time in Range (TIR) and Coefficient of Variation (CV). These are useful, but they don't tell the whole story. This study suggests that how your blood sugar moves — not just where it lands — may be just as important.

Here's what the new metrics measure:

• Rebound Hyperglycemia (RHyper): A rapid rise in blood sugar, often after a low
• Rebound Hypoglycemia (RHypo): A rapid drop in blood sugar, often after a high
• Extended Hyperglycemia (EHyper): Blood sugar staying dangerously high for a prolonged period
• Extended Hypoglycemia (EHypo): Blood sugar staying dangerously low for a prolonged period

Key Patterns the Researchers Noticed

The study found some clear patterns in when these events happen:

• High blood sugar swings (RHyper) and extended highs (EHyper) happened more often during the day and increased as the day went on — possibly tied to meals and activity
• Extended lows (EHypo) happened mostly at night, which is especially concerning because many people sleep through these dangerous episodes
• Rebound highs and rebound lows were very closely linked to each other — when one went up, the other tended to follow

What the Numbers Showed

The average Time in Range for the group was about 62%, and average glucose was 173 mg/dL. The researchers found that the new rebound metrics were strongly tied to Coefficient of Variation (CV) — a measure of how much your glucose bounces around. This means if your CV is high, you're more likely to experience these dangerous swing patterns.

Importantly, rebound events were better at predicting low blood sugar episodes caused by glucose variability than some standard CGM measures. This suggests these new metrics could one day help doctors and patients catch problems earlier.

What This Means in Real Life

This research is still in early stages, and these new metrics aren't yet a standard part of most CGM reports. But the findings suggest that paying attention to how fast your blood sugar is moving — not just the number on the screen — could help prevent dangerous highs and lows. If you notice your glucose frequently bouncing up and down, that pattern itself is a warning sign worth discussing with your care team.

Tracking your CGM data consistently and reviewing it regularly with your doctor gives you the best chance of catching these patterns. Tools and supplies that support reliable, consistent CGM use — like those available at mdsdiabetes.com — help make sure your device is always working when you need it most.

Citation

Akturk, Karakus, Chen (2026). Exploring the Relationship Between Newly Defined Continuous Glucose Monitoring (CGM) Metrics and the Standard CGM Metrics in 30,000 People with Type 1 Diabetes. Diabetes Technology & Therapeutics. PMID: 40948018. DOI: 10.1177/15209156251377797