Real-Time CGM Plus Insulin Pump Best for Type 1 Diabetes

Miriam E. Tucker

February 22, 2023

Youth with type 1 diabetes who use real-time continuous glucose monitoring (rtCGM) and an insulin pump spend more time in target glucose range than those using intermittently scanned CGM (isCGM) and/or multiple daily insulin injections, new data show.

In the multinational cohort study of more than 4500 people younger than age 21 with type 1 diabetes, those using rtCGM and pumps also spent less time above and below glucose targets and had fewer severe adverse events — either severe hypoglycemia or diabetic ketoacidosis (DKA) — compared with injections and isCGM.

The findings were published online in JAMA Network Open by Klemen Dovc, MD, PhD, assistant professor in the department of pediatric endocrinology, diabetes, and metabolic diseases, University Children's Hospital, Ljubljana, Slovenia, and colleagues.

"These results underscore the synergistic effect of advanced diabetes technologies that should be more readily available to youths with type 1 diabetes for further improvement of diabetes-related clinical outcomes," the authors write.

Moreover, Dovc told Medscape Medical News: "Clinicians should be aware that there may be differences in effectiveness between different types of devices, and that choosing the right device for each individual may be important for achieving optimal outcomes."

Real-Time CGM + Insulin Pump = Highest Time in Range

The researchers explain that two modalities of CGM are broadly available: rtCGM, which continuously displays glucose concentration in the interstitial fluid (usually at intervals of 1-5 minutes) on a dedicated receiver or other portable device, such as a smartphone, and provides various adjustable alarms, and isCGM, which displays data on demand when the transmitter is scanned using either a dedicated reader or smartphone-based application.

rtCGMs include devices from Dexcom and Medtronic. The isCGM, or "flash", generally refers to the Abbott FreeStyle Libre.

The study included just over 4500 individuals younger than 21 years from 34 centers in 21 countries in the SWEET registry, a worldwide network of diabetes care centers for youth, between January 1, 2016, and December 31, 2021.

The researchers didn't report which particular devices were used in the trial, rather they just divided patients into four groups: 850 used isCGM with a pump, 1231 used isCGM with multiple daily injections, 2252 used rtCGM with a pump, and 886 used rtCGM with insulin injections.

After adjustments for sex, age, diabetes duration, and body mass index (BMI) standard deviation score, rtCGM plus insulin pump was the most likely group to achieve the recommended greater than 70% time in target glycemic range (70-180 mg/dL), with 36.2% achieving it, followed by rtCGM plus injections, at 20.9%, and isCGM plus injections, at 12.5%. Those using isCGM with an insulin pump were the least likely to achieve time in range, at just 11.3%.

Similar trends were seen for the recommended goal of less than 4% of time spent below range (< 70 mg/dL) and less than 25% of time spent above range (> 180 mg/dL). Those using rtCGM with a pump had the highest proportions achieving both of those goals, 73.1% and 32.5%, respectively.  

The use of rtCGM, with or without a pump, was associated with lower rates of severe hypoglycemia (2.5% and 2.0%, respectively) than isCGM with or without a pump (5.5% and 5.2%, respectively).

Similarly, the proportion experiencing at least one DKA episode varied from 1.4% for rtCGM plus insulin pump and 0.7% for rtCGM plus injections to 3.0% for isCGM plus pump and 1.5% isCGM plus injections.

Study Looked at Older Technology but Results Still Reflect Benefit

Among the rtCGM plus insulin pump group were 264 participants (5% of the total study population) recorded in the database as using automated insulin delivery (AID) systems, also known as the artificial pancreas, although this is likely an undercount as the presence of communication between the two devices was not automatically recorded, Dovc explained.

Those individuals recorded as using AIDs had a higher unadjusted time in range compared with non-AID users (66.3% vs 59.0%) and lower time above range (30.1% vs 37.0%) but didn't differ in time below range (2.9% vs 3.0%).

Dovc told Medscape Medical News: "While automated systems are becoming more common, there are still many individuals who do not have access to glucose-responsive devices, including lack of reimbursement, or decide not to use them."

But, he added, "Despite the low reported numbers of AID users, results achieved in the pump with real-time CGM [group] are admirable and approaching recommended consensus targets with a clinically meaningful difference towards all other treatment modalities. As our findings may not be directly applicable to all participants using automated systems, they may still provide useful insights into the factors that influence glycemic control."

Similarly, the intermittently scanned CGMs used by most in the study, and particularly in the earlier period, didn't have low- or high-glucose alarms as do later versions. And an even more recent version also doesn't require scanning either, so is essentially also "real-time."

Dovc noted, "in the first half of our observational period only first generation of intermittently-scanned CGM was generally available, and we can speculate that only a small proportion started to use second generation towards the end of our observational period. The exact number of second-generation users was not available in this analysis."

He also acknowledged that because the study was observational and not randomized, patient choice of device could have influenced the outcomes.

"For example, participants who choose to use a more expensive device may have more resources or support available to them, which could influence their ability to manage their diabetes effectively. Additionally, individuals who choose to use a particular device may be more motivated or engaged in their diabetes care, which could also impact their outcomes. It would be important for future studies to explore the impact of device selection on device effectiveness and to control for this potential confounding factor in the analysis."

This study was supported by the international Better Control in Pediatric and Adolescent Diabetes: Working to Create Centers of Reference (SWEET) corporate members, including Abbott Laboratories, Boehringer Ingelheim, Dexcom, Insulet, Eli Lilly, Medtronic, Sanofi, and the Slovenian National Research Agency. Dovc has reported receiving speaker's fees from Abbott Laboratories, Medtronic, and Novo Nordisk; participating on advisory boards for Eli Lilly and Pfizer outside the submitted work; and serving as a member of the European Commission Expert Panel for Medical Devices for Endocrinology and Diabetes.   

JAMA Netw Open. Published online February 20, 2023. Full text

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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