Is real time glucose monitoring better than intermittent scanning for patients with type 1 diabetes?

This study compared intermittent scanning continuous glucose monitoring (isCGM) with real-time continuous glucose monitoring (rtCGM) for the treatment of type 1 diabetes (T1D). It found that compared to isCGM, rt CGM resulted in increased time spent in range and improved blood glucose control in these patients. 

Type 1 diabetes (T1D) is a condition where the pancreas cannot produce insulin to control blood glucose (sugar). Therefore, insulin treatment has to be given to maintain normal blood glucose levels. Blood glucose levels used to be measured by finger prick. However continuous glucose monitoring (CGM) is now the better choice. CGM involves a sensor that the patient wears all the time which can check the blood glucose as often as necessary. 

There are different types of CGM. Intermittent scanning CGM (isCGM) checks the blood glucose whenever the patient asks it to by using a sensor on their phone. Real-time CGM (rtCGM) checks the blood glucose continually, every 1-5 minutes, and issues an alert if the reading is too high or too low. It is unclear whether rtCGM is necessary to improve blood glucose control in patients with T1D.

This study was completed by 229 patients with T1D across 6 hospitals in Belgium. Patients were divided into two groups. Group 1 used isCGM for 6 months, then switched to rtCGM for the next 18 months. Group 2 used rtCGM for the full 24 months. Both groups were monitored to determine the amount of time they spent in the correct blood glucose range (time in range -TIR), the time they spent with very low blood glucose levels (less than 3.00 mmol/L; hypoglycemia), and their HbA1c (blood glucose control over the past 2-3 months).  

At 24 months, both groups noted an improvement in TIR. In group 1 TIR increased from 51.8% at the start of month 6 to 63.5% after 18 months of rtCGM.  In group 2 TIR increased from 52.5% to 63% after 24 months of rtCGM. 

Both groups also noticed a decrease in HbA1c. Group 1 noted a drop in HbA1c from 7.4% at month 6 (start of rtCGM) to 6.9%, while group 2 had a similar drop from 7.4% to 7.0% after 24 months. There was a reduction a time spent in hypoglycemia in both groups on rtCGM. In group 1 time in hypoglycemia dropped from 0.84% at the start of month 6 to 0.56% at month 12 and remained stable after that. In group 2 time in hypoglycemia dropped from 0.91% to 0.58% at month 12 and remained stable after that. 

Patients reported high quality of life and fewer emotional problems related to diabetes while using the rtCGM. 

This study showed that compared to isCGM, rtCGM resulted in longer time spent in range and better blood glucose control, with reduced emotional problems in patients with T1D.

This study used first-generation devices which have very recently been overtaken by newer devices on the market. Further study is required to see if these results remain the same using the newest technology. This study was funded by Dexcom, the manufacturer of rtCGM devices.