This study compared the accuracy of two continuous glucose monitoring systems for type 1 diabetes. 

Patients with type 1 diabetes do not produce insulin (the hormone needed to break down glucose). Treatment involves replacing the insulin, either through injections or with an insulin pump (a machine that continuously delivers insulin through a tube inserted through the skin). Because insulin therapy can increase the risk of hypoglycemia (dangerously low blood glucose), patients must actively monitor their blood glucose. 

Continuous glucose monitoring (CGM) systems measure blood glucose levels on a constant basis. A CGM involves a sensor inserted under the skin that measures blood glucose levels. Levels are transmitted to a device that alerts the patient when glucose levels dip too low. Two of the most widely used systems are the Dexcom G4 Platinum (DG4P) and the Medtronic Paradigm Veo Enlite (MPVE).

CGM systems are not completely accurate, especially during hypoglycemia. Few studies have compared the accuracy of different CGM systems, particularly in the home setting where patients use them. Determination of the accuracy of CGM systems in the home setting would be useful for patients and healthcare providers.

This study compared the accuracy of the DG4P and MPVE CGM systems being used by type 1 diabetes patients in the home and in the lab.

24 patients took part in the study. The patients visited the hospital to have both types of CGM fitted. Patients stayed at the hospital for 6 hours. Regular blood glucose tests were taken by injection. The patients then went home and used the CGMs for 6 days. At home, the patients also regularly checked blood glucose levels with a finger prick test.

The average difference between hospital blood glucose test results and the results of the CGM were 13.6% for the DG4P and 16.6% for the MPVE. The average difference between the home finger prick test results and the CGM results was 12.2% for the DG4P and 19.9% for the MPVE. For both CGM systems, the overall average difference was higher during hypoglycemia (glucose levels 3.9 mmol/l or less) than during euglycaemia (glucose levels 3.9–10 mmol/l). For the DG4P, the average difference during hypoglycemia was 17.6%, in comparison to 13.0% during euglycemia. For the MPVE, the average difference was 24.6% during hypoglycemia and 14.2% during euglycemia. 

This study concluded that the DG4P system was more accurate than the MPVE system. It was also noted that while both systems were less accurate during hypoglycemia, the MPVE system showed a greater reduction in accuracy during hypoglycemia than the DG4P system.

This study was funded by Dexcom, the company that produces the DG4P. 

Consult your doctor if you are concerned about the accuracy of your CGM system.