Editor’s Comment: “It Ain’t Necessarily So”

As much as we may wish to believe that diabetes education per se leads to improved long-term glycemic outcomes, the evidence is not particularly strong. The review by Norris et al. (1), to which the letter by Sone et al. (3), above, is addressed, and an earlier one by Clement (2) do not support this contention. Likewise, neither does the accompanying letter by Sone et al. (3). They contend that the 0.16% difference in HbA_1c levels after 3 years between an intervention group receiving diabetes self-management education and a control group receiving regular conventional care in the Japanese Complications Study would be “clinically meaningful because each 1% reduction in HbA_1c levels over 10 years has been shown to be associated with a 37% reduction in the risk of microvascular complications in the U.K. Prospective Diabetes Study (UKPDS) (4).” Unfortunately for the hypothesis, it is an average reduction of 1% in HbA_1c levels per year over 10 years—not a cumulative decrease over 10 years—that leads to this favorable outcome.

For those of you who remember trying to prove mathematical theorems, the concepts of necessary and sufficient are germane, in my view, to the situation concerning diabetes education and glycemic outcomes. Certain conditions are necessary to prove theorems, but they won’t do it by themselves. On the other hand, for some theorems, if a specific condition is met, it is sufficient to prove that theorem all by itself. I think of diabetes education as a necessary condition, but without an appropriate management component, it is not sufficient. On the other hand, without appropriate education, a management piece is usually not all that effective. Therefore, in this analogy, the difficulty of showing the effectiveness of diabetes self-management education is that patients often return to medical environments in which appropriate management is lacking.