Continuous glucose monitoring is more sensitive than HbA1c and fasting glucose in detecting dysglycaemia in a Spanish population without diabetes

Abstract

AimsTo investigate whether continuous glucose monitoring (CGM) reveals patterns of glycaemic behaviour, the detection of which might improve early diagnosis of dysglycaemia. MethodsA total 1521 complete days of valid CGM data were recorded under real-life conditions from a healthy sample of a Spanish community, as were matching FPG and HbA1C data. No participant was pregnant, had a history of kidney or liver disease, or was taking drugs known to affect glycaemia. ResultsCGM and fingerstick measurements showed a mean relative absolute difference of 6.9 ± 2.2%. All subjects were normoglycaemic according to FPG and HbA1C except 21% who were prediabetic. The normoglycaemic subjects had a 24-hour mean blood glucose concentration (MBG) of 5.7 ± 0.4 mmol/L, spending a median of 97% of their time within the target range (3.9–7.8 mmol/L). 73% of them experienced episodes with blood glucose levels above the threshold for impaired glucose tolerance, and 5% levels above the threshold for diabetes. These normoglycaemic participants with episodes of high glycaemia had glycaemic variabilities similar to those of prediabetic subjects with episodes of similar intensity or combined duration. ConclusionsCGM is a better indicator of possible early dysglycaemia than either FPG or HbA1c.