More evidence needed on the benefits of CGM in children with type 1 and adults with type 2

SMBG

Previous systematic reviews and meta-analyses have failed to turn up clear evidence on the benefits and harms of continuous glucose monitoring (CGM) in children with type 1 diabetes and insulin-using patients with type 2 diabetes.

This systematic review set out to update this state of affairs in the light of recent studies.

  1. In children with type 1 diabetes, does CGM as compared with Self Monitoring of Blood Glucose (SBMG) lead to improved glycaemic control?
  2. In adults with type 2 diabetes using insulin, does CGM as compared with SMBG lead to improved glycaemic control?

Methods

The reviewers searched Pubmed, Scopus, CINAHL, Web of Science and The Cochrane Library.

As well as the overall impact on HbA1c, the authors examined sub-groups according to the type of CGM device and baseline HbA1c.

A child tests her blood sugarResults

In children with type 1:

The reviewers found ten RCTs with a total of 817 participants.  Meta-analysis found no significant difference between the groups in HbA1c (mean difference -0.13%, 95%CI -0.38% to 0.11%).

In adults with type 2:

Five RCTs comprising 161 participants were included.  The analysis found that CGM produced a significantly greater reduction in HbA1c compared with SMBG: 0.31% (95%CI -0.6% to -0.02%).

The reviewers’ conclusion was:

The use of CGM did not provide better efficacy than SMBG use in terms of HbA1c reduction in T1DM pediatrics.  [However,] CGM can be a useful tool to reduce HbA1c level in type 2 diabetes adults.

Comments

  • The search strategy was not very sophisticated and may have missed some articles.  Also, it is not clear whether EMBASE was searched.
  • The reviewers reported substantial heterogeneity between the studies, suggesting that there were important differences between them.  The studies also varied significantly in their sample size and quality.
  • The results of this review will undoubtedly be affected by changes in technology.  There was evidence, for example, of differences between real-time and retrospective CGM.
  • Another key issue with such research is the difficulty in dealing with confounding.  Simply monitoring data on its own cannot help.  The data must be acted upon in some way in order to improve glycemic control.  The reviewers comments that there were important differences between the type 2 studies in this respect, with one study in particular containing important lifestyle co-interventions alongside CGM.
  • The evidence remain sketchy for both of these population groups.
  • We need carefully designed, large-scale randomised trials to establish the effectiveness of specific types of CGM technology.

Reference

Poolsup N, Suksomboon N, Kyaw AM.  Systematic review and meta-analysis of the effectiveness of continuous glucose monitoring (CGM) on glucose control in diabetes. Diabetol Metab Syndr. 2013; 5: 39.