Spotlight on innovative uses of CGM

Recent trials indicated effectiveness of open-source automated insulin delivery systems, inpatient insulin management based on continuous glucose monitoring (CGM), and CGM for certain patients with type 2 diabetes who are not taking insulin.

Several recent studies looked at innovative ways for patients with diabetes to benefit from continuous glucose monitoring (CGM).

The first, published by the New England Journal of Medicine on Sept. 8, was an open-label trial of an open-source automated insulin delivery (AID) system, a version of the commercial systems that offer an insulin pump, CGM, and algorithm to provide “closed-loop” glucose control that is freely available and used on Android phones. The trial randomized 97 patients with type 1 diabetes (48 children and 49 adults) to use an open-source AID system (n=44) or a sensor-augmented insulin pump (n=53). All patients previously used an insulin pump but had no experience with the open-source AID system. At 24 weeks, the mean time in the target range of 70 to 180 mg/dL (3.9 to 10.0 mmol/L) increased from 61.2% to 71.2% in the AID group and decreased from 57.7% to 54.5% in the control group (P<0.001), with no treatment effect according to age. The authors noted that the improvement in time in range with the open-source AID system compared to the control is equivalent to that seen with commercial AID systems in manufacturers' trials.

An accompanying editorial noted that such commercial systems have advanced slowly and carry a number of limitations, including limited customizability, availability, access, and cost. “In response to such delays and limitations, open-sourced configurations, commonly known as do-it-yourself solutions, have allowed patients to program a system for their personal use by means of open-source documents maintained and supported primarily by other members of the type 1 diabetes community,” said the editorial. “This trial of an open-source configuration showed the superior performance of an AID system in yet another clinical trial … these advances need to be accompanied by efforts to ensure that these beneficial systems are equitably accessible.”

The second study, published by Diabetes Care on Aug. 19, was a manufacturer-funded trial of a CGM device in hospital patients. It included 185 medical and surgical patients with type 1 and type 2 diabetes treated with basal-bolus insulin, randomized to insulin dose adjustment based on either point-of-care (POC) capillary glucose testing before meals and bedtime or their daily CGM profile. All patients underwent POC glucose testing and had the CGM monitors, but in the POC groups, clinicians were blinded to the CGM monitors. The groups showed no significant differences in time in target range, mean daily glucose, or hypoglycemia. Among patients with one or more hypoglycemic events, the CGM group had less hypoglycemia recurrence and spent less time with hypoglycemia. The study authors concluded that the CGM system was safe and effective for inpatients and comparable to POC-guided insulin adjustment. “Importantly, the reduction in recurrent hypoglycemic events was seen overnight, a time that POC is rarely checked,” they added. The authors noted that the FDA issued a nonobjection statement to inpatient CGM use during the pandemic but has not yet approved the devices for this setting.

The final study, published by Diabetes, Obesity and Metabolism on Aug. 28, tested CGM in patients with uncontrolled diabetes treated with three or more oral agents but not insulin. It included 61 participants, randomized to three arms: one weeklong session of CGM, two sessions of CGM with a three-month interval between sessions, and a control group. A total of 48 patients completed the study, and both CGM groups showed a significant reduction in HbA1c at three months compared to controls. However, at six months, only the group receiving two sessions achieved a significant HbA1c reduction (-0.68% P= 0.018). The authors noted that patients performing self-monitoring of blood glucose at least 1.5 times per day showed significant HbA1c improvement at both three months and six months, while those who self-monitored less often did not. They concluded that intermittent short-term use of CGM was an effective method for glucose control, especially in patients who frequently monitor their glucose. The authors noted that for patients with uncontrolled type 2 diabetes who do not want to take insulin, CGM “may be a reasonably attractive substitute.”