Living With T1D/August 15, 2026/2 min read

What Happens to Weight and Blood Sugar When You Start Using a CGM?

A large study tracked adults with Type 1 diabetes after starting continuous glucose monitoring and found that most people had stable weight while improving their blood sugar control—but a smaller group gained more weight than expected.

PubMed indexed literature

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Key takeaways

After 2 years on CGM, most adults saw their HbA1c improve slightly while gaining only 1–2 kg on average
About 8 in 10 people had stable weight and steady blood sugar—the most common pattern
A smaller group (roughly 1 in 10) gained substantial weight without improving blood sugar control
CGM users who gained weight still showed better HbA1c outcomes than people who didn't use CGM

The Study: Tracking Real-World Outcomes

Researchers followed over 4,100 adults with Type 1 diabetes across two European registries as they started using continuous glucose monitoring (CGM). They tracked what happened to body weight and HbA1c—a measure of average blood sugar over time—for up to 24 months. A comparison group of similar adults who didn't use CGM was also monitored to help understand whether changes were due to CGM itself or other factors.

The Main Findings: Weight and Blood Sugar Improved for Most

After 2 years, the typical CGM user gained between 1 and 2 kg while their HbA1c dropped by roughly 0.1–0.2%. These improvements occurred in both study groups and were small but statistically significant. People who didn't use CGM also gained weight and saw small HbA1c improvements, but their changes were generally smaller than those using CGM.

Three Different Patterns Emerged

Rather than everyone following the same path, researchers identified three distinct groups. The largest group—about 8 in 10 people—maintained stable weight while keeping their blood sugar steady. A smaller group (roughly 1 in 5 in one cohort, 1 in 15 in another) had modest weight gain alongside improved HbA1c. A third, smaller group gained a substantial amount of weight (around 8 kg) without improving their blood sugar control. Importantly, this unfavorable pattern was less common in CGM users than in people who didn't use CGM.

What This Means for People Using CGM

This study suggests that for most adults, starting CGM is associated with stable weight and modest improvements in blood sugar control. While weight gain is possible, it appears to be modest for the majority. A minority of people do experience more significant weight gain, and this may warrant attention—though the reasons why some people follow different patterns remain unclear. If you're considering or already using CGM, these results provide reassurance that weight gain is not an inevitable side effect, though individual experiences vary.

Evidence label

Source: The Lancet regional health. Europe. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.

Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.

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