More evidence needed for direct telephone support in diabetes care

An asian woman on the phone

There’s lots of interest in how we can use the increasingly ubiquitous telephone to improve diabetes care.  It’s important that we apply the same rigorous tests to these interventions as we do to others, and don’t just assume that “new” means “better“.

In resource-poor settings this is all the more important, as we have to make sure we can make the best use of the resources we have.

A new systematic review in Public Library of Science One (PLoS ONE) looked at telephone interventions for people with diabetes compared with standard care.  Glycated haemoglobin (HbA1c) was the primary outcome.


The reviewers searched the literature for randomised trials comparing direct telephone interventions with usual care.

They restricted themselves to telephone-only interventions (as opposed to telephone support plus other interventions or information exchange) because they felt this best reflected the reality of resource availability developing world settings.

The studies were quality-checked by two blind, independent reviewers using a validated instrument.


Five trials involving 953 patients met the inclusion criteria and contributed to the meta-analysis.

The telephone interventions used in the trials varied.  They included clinical advice on management of medication, diabetes education, peer support, problem-solving approaches and psychological support.

When the reviewers pooled all of the data from these trials in a meta-analysis, they found that the difference in HbA1c between patients given direct telephone support and those on usual care was not statistically significant.

The forrest plot

Figure 2. Mean difference (95% CI) in the changes of HbA1c from baseline for phone call intervention and standard clinical care:  doi:10.1371/journal.pone.0089207.g002


The reviewers concluded that:

Telephone contact intervention was no more effective than standard clinical care in improving glycemic control (pooled mean difference in HbA1c −0.38%, 95%CI −0.91 to 0.16%).

However, we can’t rule out the possibility that more research won’t prove these approaches to be beneficial.  Further trials are needed, measuring other outcomes and over a longer period.


  • The reviewers didn’t include EMBASE in their search, so there might have been other studies that they missed.  They also failed to perform hand searching and citation searching (although Web of Science is cited as a source, which provides access.
  • We might question the decision to exclude studies that used a telephone intervention alongside a co-intervention such as electronic data transmission, such as SMS text messaging, SMBG support or self-adjustment of medication.  It seems that this would exclude a lot of similar literature and may have limited the statistical power of the review.
  • Some of the studies had methodological problems – small sample size, unclear or inadequate allocation concealment, lack of intention-to-treat.  A familiar pattern!
  • The largest study showed a modest but statistically significant benefit in type 2 diabetes, suggesting it is worth doing more research.
  • Heterogeneity is always an issue with this type of review.  The review mixed studies of type 1 and type 2 diabetes.  The interventions were different, and the durations were different.  All the more reason for more research.
  • Telephone interventions certainly offer significant potential for developing countries, due to the rapid expansion of mobile phone networks.


Suksomboon N, Poolsup N &  Nge YL.  Impact of Phone Call Intervention on Glycemic Control in Diabetes Patients: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials.  PLoS ONE February 19, 2014; DOI: 10.1371/journal.pone.0089207.