Continuing versus discontinuing CGM in people with type 2 diabetes

Results of the MOBILE study, in which people with type 2 diabetes poorly controlled with basal insulin were randomised to continuous glucose monitoring (CGM) or capillary blood glucose monitoring (BGM), have been published recently (Martens et al, 2021). After 8 months of intervention, HbA_1c in the CGM group decreased by 12 mmol/mol (to 64 mmol/mol), while in the BGM group it fell by 7 mmol/mol (to 68 mmol/mol). The CGM group also saw an increase in time in range (TIR) of 3.6 hours per day and a decrease in time below range of 3.8 hours per day.

In this continuation of the MOBILE study, the authors sought to determine the effects on glycaemic control of continuing versus discontinuing CGM for the subsequent 6 months. Participants in the original CGM group were randomised to continue CGM (n=53) or to switch to BGM (n=53), and they were also compared with participants in the BGM group who continued to self-monitor (n=57). Participants in the latter two groups wore masked CGM devices for the purpose of assessing TIR parameters.

In the group that continued CGM, mean TIR remained stable, increasing from 56% to 57% (having risen from 44% at study initiation). In contrast, the group that discontinued CGM experienced in a fall in TIR from 62% to 50% (having risen from 38% at study initiation). In the BGM group, TIR increased from 41% at study initiation to 43% at 8 months and 45% at 14 months.

There were few changes to glucose-lowering therapy, including daily insulin doses, over the study follow-up; therefore, the authors conclude that the reduction in glycaemic control observed in the discontinuation group could be attributed mainly to behavioural changes triggered by the lack of CGM cues regarding glucose levels.

The authors conclude that discontinuing CGM resulted in a loss of nearly half of the improvements in TIR that were achieved during CGM use. However, the fact that some of the improvement persisted suggests that there could be lasting benefits of a period of CGM use, possibly as a result of lifestyle and diet modifications or improved medication adherence. The study also suggests that continuing CGM use over the longer term results in sustained improvements in glycaemic control in this group of patients with type 2 diabetes.

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