Continuous glucose monitoring reduced hypoglycemia over 6 months

Older adults with type 1 diabetes who were randomized to continuous glucose monitoring (CGM) had a small but statistically significant improvement in hypoglycemia compared with those who used standard blood glucose monitoring (BGM), a trial found. One episode of severe hypoglycemia was reported in the CGM group, compared to 10 among BGM patients. The trial devices were provided by Dexcom.

The study was published in the June 16 issue of JAMA and summarized in the July ACP Diabetes Monthly. The following commentary by Darin E. Olson, MD, PhD, was published in the ACP Journal Club section of the Nov. 17 Annals of Internal Medicine.

Older patients with type 1 diabetes require better management of hypoglycemia. Trials have shown that CGM reduces severe hypoglycemia, but participants have predominantly been younger adults. Physicians may hesitate to suggest advanced technology for older adults.

Pratley and colleagues found that CGM reduced hypoglycemia and modestly improved glycemic control in adults aged ≥60 years with type 1 diabetes (median duration ≥36 y; mean HbA1c, 7.5%) compared with standard of care fingerstick BGM ≥4 times/d. Patients in the CGM group had more unscheduled office visits and phone calls, additional guidance to adjust treatment based on glucose trends and absolute values, and alarms when blood sugar was low or going to be low. The primary outcome of time with glucose <70 mg/dL [<3.9 mmol/L] was reduced, but the absolute difference of only 2% of the day needs to be put into perspective (i.e., range of 19 to 52 min/d with CGM vs. 37 to 158 min/d with BGM).

The reduction in severe hypoglycemia events with CGM is more striking. As severe hypoglycemia is associated with falls, cognitive decline, and adverse cardiovascular events in older patients, the findings support a recommendation of CGM for older adults with type 1 diabetes. HbA1c was modestly reduced with CGM alongside fewer hypoglycemia events, suggesting that intensive glycemic control can be more safely achieved in older patients who use CGM, potentially lowering their risk for long-term complications.

Can these data extrapolate to other CGM devices? Newer versions of the Dexcom CGM are easier to use and do not require calibration to BGM (Dexcom G6). Other “fully functional” CGMs (e.g., Medtronic Guardian) have similar function and cost but require calibration. A less expensive option is intermittently sampled, or “flash” CGM (e.g., Freestyle Libre) with readings as frequently as every minute, but users must actively check the monitor. The current Freestyle Libre model lacks a low glucose alarm, so it may not reduce severe hypoglycemia to the same extent as seen in the trial by Pratley and colleagues. However, a new iteration of Freestyle Libre has been approved with alarms, making it more similar to the CGM used in this trial.