Comment on Aleppo et al. The Effect of Discontinuing Continuous Monitoring in Adults With Type 2 Diabetes Treated With Basal Insulin. Diabetes Care 2021;44:2729–2737

Aleppo et al. (1) have published an extension of the Continuous Glucose Monitoring in T2D Basal Insulin Users: The MOBILE Study (MOBILE) (2), both of which showed that in patients receiving basal insulin alone under the care of primary care providers (regardless of noninsulin drugs), continuous glucose monitoring increased the time spent in the target time in range (TIR) 70–180 mg/dL. Time spent in the target TIR has been shown in two randomized control trials and seven cross-sectional studies to be inversely associated with diabetes-related complications (see references in Aleppo et al. [1]). The fact that preprandial glucose concentrations are the most important determinants of postprandial glycemia (3) strongly suggests that fasting plasma glucose (FPG) concentrations will have a major effect on TIR, especially during the daytime. Based on this postulate, it has been recommended that in patients receiving basal insulin alone, consideration of the need to intensify the insulin regimen should be withheld until FPG targets have been achieved (3). In those patients who achieved FPG targets, one-third to one-half reached an A1C level of <7.0% (4,5). If the insulin regimen is intensified before FPG targets are achieved, usually by adding preprandial short- or rapid-acting insulin, a large number of patients will unnecessarily be subject to the increased risk of hypoglycemia, increased injections, increased glucose monitoring requirements, and the inconvenient impact on their lifestyles that is associated with basal/bolus and other intensified insulin regimens. Furthermore, adding preprandial insulin will have little effect on achieving FPG targets.

The MOBILE studies (1,2) offer a unique opportunity to evaluate the relationship between FPG concentrations and the daytime TIR, which is presented in Supplementary Table 8 in Aleppo et al. (1). A high correlation between the two at each visit would support the approach of not considering intensification of the insulin regimen in patients receiving basal insulin alone until FPG targets are reached and spare a large number of patients from intensified insulin regimens. Would the authors consider carrying out these inverse correlations? Since daytime glycemia is the most important factor related to A1C levels once FPG concentrations are at target, TIR at this juncture will be more meaningful in predicting diabetes complications.