We read with interest the recently published meta-analysis by Norris et al. (1), which focuses on the effects of diabetes self-management education (DSME) on glycemic control in adult patients with type 2 diabetes. They report that this intervention decreases patients’ GHb levels by 0.76% at immediate follow-up, by 0.26% at the 1- to 3-month follow-up and by 0.26% at ≥4 months of follow-up. They conclude in both this meta-analysis and their previous systemic review (2) that DSME alone moderately but significantly improves GHb levels in the short term but that its long-term effects still need to be determined in a study of randomized controlled intervention.

As part of the Japan Diabetes Complications Study (JDCS), we have been evaluating the long-term effects of DSME for >5 years in 2,205 adult patients with type 2 diabetes. Our study is longer and involves more patients than any of the trials included in the meta-analysis by Norris et al. Ours is a randomized, controlled, multicenter, intervention trial that aims to evaluate the effects of DSME. The trial involves 59 institutes specializing in diabetes care, and the 3-year interim report will be published shortly (3). In brief, we randomly allocated patients with previously diagnosed type 2 diabetes and HbA1c levels of ≥6.5% into either an intervention (INT) group or a control (CON) group. The patients in the CON group received regular conventional care before or during the study period. Although changes in medication were not restricted in either group, there were no significant differences in terms of therapeutic contents between the CON and INT groups even after 3 years. The patients in the INT group received DSME, which comprised all of the categories that Norris et al. included in their meta-analysis (1) and consisted mainly of intensive lifestyle management at each outpatient clinic visit and frequent telephone counseling by trained diabetes educators. Our results show that there are small but significant differences in HbA1c levels between the INT and CON groups that are still maintained 3 years after the start of intervention (CON group 7.78 ± 1.27% vs. INT group 7.62 ± 1.20%, P = 0.0023). Although the difference between the two groups is small, it should be noted that a bias arising from variations in the techniques of GHb measurement, as discussed by Norris et al. (1), does not exist in Japan, where a highly standardized assay is used throughout the country. Therefore, the difference in the JDCS study is likely to be a realistic measurement of the effect of DSME intervention.

The improvement in GHb levels of <1% seen in the results of the meta-analysis (1), as well as in our longer-term trial (3), seems to be clinically trivial and disappointing as compared with medical interventions (i.e., drugs or insulin). As Norris et al. discuss in their article (1), however, it is still clinically meaningful because each 1% reduction in HbA1c levels over 10 years has been shown to be associated with a 37% reduction in the risk of microvasular complications in the U.K. Prospective Diabetes Study (UKPDS) (4). We expect that further meta-analyses regarding differences in long-term costs and the patients’ quality of life between DSME and medications that lower GHb levels will be carried out. In the JDCS, however, the long-term effects on lifestyle brought about by DSME and the cost of its implementation are already under analysis.

In summary, on the basis of the large-scale JDCS trial, we can conclude that the moderate but significant improvement effected by DSME on the glycemic control of adult patients with type 2 diabetes is maintained even in the long term.

Norris SL, Lau J, Smith SJ, Schmid CH, Engelgau MM: Self-management education for adults with type 2 diabetes: a meta-analysis of the effect on glycemic control.
Diabetes Care
Norris SL, Engelgau MM, Narayan KM: Effectiveness of self-management training in type 2 diabetes: a systematic review of randomized controlled trials.
Diabetes Care
Sone H, Katagiri A, Ishibashi S, Abe R, Saito Y, Murase T, Yamashita H, Yajima Y, Ito H, Ohashi Y, Akanuma Y, Yamada N, JDCStudy Group: Effects of lifestyle modifications on patients with type 2 diabetes: the Japan Diabetes Complications Study (JDCS) study design, baseline analysis and three year-interim report.
Horm Metab Res,
In Press.
Stratton IM, Adler AI, Neil HA, Matthews DR, Manley SE, Cull CA, Hadden D, Turner RC, Holman RR: Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study.
Br Med J

Address correspondence to Nobuhiro Yamada, MD, PhD, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan 305-8575. E-mail: jdcstudy@md.tsukuba.ac.jp.