Italian Study Confirms Continuous Glucose Monitors Work for Both Type 1 and Type 2 Diabetes

A study from Italy, conducted by researchers at the University of Campania "Luigi Vanvitelli" in Naples, offers some of the strongest evidence yet that continuous glucose monitors (CGMs) meaningfully improve blood sugar control — and the benefits apply whether you have Type 1 or Type 2 diabetes.

What the Researchers Did

The Italian team performed a meta-analysis — essentially a large-scale review that pools data from multiple studies — examining 15 randomized controlled trials involving 2,461 patients with diabetes. These trials ran between 12 and 36 weeks and compared people using CGMs against those receiving standard diabetes care. The researchers looked at several key markers: HbA1c (your 3-month average blood sugar), time in target range (TIR), time above range (TAR), time below range (TBR), and glucose variability.

Key Findings

Patients using CGMs gained an average of 70 minutes per day in their target blood sugar range compared to those using standard care. In plain terms: if you wore a CGM, your blood sugar spent more than an hour longer each day in a healthy zone. For those using real-time CGMs specifically — the kind that display your glucose level continuously on a screen or app — the benefit was even greater, with an additional 83 minutes per day in range.

CGM users also saw a modest but meaningful reduction in HbA1c of 0.17% overall, rising to 0.23% for real-time CGM users. While these numbers may seem small, research consistently shows that even modest HbA1c reductions lower the risk of complications like kidney disease and nerve damage.

Importantly, CGMs also reduced dangerous low blood sugar episodes (time below range), which is a critical safety concern for many patients — particularly those on insulin.

Converting the Numbers to US Terms

Italian and American researchers use the same HbA1c percentage scale, so no conversion is needed there. For blood glucose levels, the international standard target range is 70–180 mg/dL (3.9–10.0 mmol/L) — which aligns directly with the American Diabetes Association (ADA) guidelines, making these findings immediately applicable to US patients.

Why This Matters for US Patients

In the United States, CGM adoption is growing rapidly, but cost, insurance coverage, and awareness remain barriers for many patients — especially those with Type 2 diabetes, who have historically been less likely to be offered CGM technology. This Italian meta-analysis is significant because it provides strong, pooled evidence that CGMs benefit both Type 1 and Type 2 patients, regardless of whether insulin is delivered by pump or injection.

The ADA now recommends CGM use for all people with diabetes who use insulin, and increasingly for Type 2 patients on non-insulin therapies. This international research supports those expanding recommendations. If your doctor hasn't discussed CGM with you yet, this study gives you solid grounds to start that conversation — especially if managing blood sugar highs and lows is an ongoing challenge.

One important caveat: all 15 studies in this review were industry-sponsored and used an open-label design, meaning patients knew whether they were using CGM. This could influence results, so independent long-term studies would further strengthen these conclusions.

The Bottom Line

Italian researchers have added powerful international evidence to a growing global consensus: CGMs work, and they work across diabetes types. More time in your healthy blood sugar range means fewer complications down the road.

Source: Maiorino MI, Signoriello S, Maio A, et al. Effects of Continuous Glucose Monitoring on Metrics of Glycemic Control in Diabetes: A Systematic Review With Meta-analysis of Randomized Controlled Trials. Diabetes Care. 2020;43(5):1146–1156. DOI: 10.2337/dc19-1459. PMID: 32312858