A Good But Delayed Effect with Tight Control of Diabetics

When the news of a diagnosis of type 2 diabetes hits, there may well be a feeling of disbelief – “I feel perfectly well” or “medicines can take care of this” – with the result that serious control of blood sugar levels doesn’t occur for months or even years. That can make a difference, as a new British study has found. It’s reported in the New England Journal of Medicine; we summarize the findings here.

UK researchers compared two levels of blood glucose control in patients with newly-diagnosed type 2 diabetes who were enrolled in 1987. Results after 10 years showed there were significantly fewer diabetic complications in the intensively-treated patients than in those with less ‘tight’ glucose control. The researchers have presented their results from 10 years’ follow-up.

Differences between HbA1c levels in the intensive control and the less-intensive control patients disappeared within a year of the end of the 10-year trial. However, during the post-trial follow-up, the significant reduction in complications persisted, and significant reductions in heart attack frequency and all-cause mortality appeared in the intensive-control group.

In the same study (though reported separately), participants with high blood pressure were randomly assigned to tight blood pressure control (target below 150/85 mmHg) or less tight control (target below 180/105 mmHg). After 10 years, there were significant reductions in diabetes-related deaths, stroke, and other complications in the tight-control group. However, 2 years later blood pressure differences between the two groups had disappeared; during the next 10 years the differences in deaths, stroke, etc, also lessened and were no longer significant.

These findings show that the benefits of tight blood sugar control in patients with diabetes extend beyond the period of intensive treatment. The authors call this a "legacy effect". They admit that intensive treatment may have been accompanied by more emphasis on lifestyle changes (diet, exercise, etc) than in the other group, and that these changes persisted over the long term, after the official end of the study. But if that was the case, why wasn’t there a comparable long-term benefit on blood pressure control? A mystery, that remains to be solved. On the meantime, newly-diagnosed diabetics should act quickly and sufficiently to get their blood glucose level under control, and kept there.