Two large studies involving more than 21,000 people found that people with Type 2 diabetes had no reduction in their risk of heart attacks and strokes and no reduction in their death rate if they rigorously controlled their blood sugar levels.

The results provide more details and bolster findings reported in February, when one of the studies, by the National Institutes of Health, ended prematurely. At that time, researchers surprised diabetes experts with the announcement that study participants who were rigorously controlling their blood sugar actually had a higher death rate than those whose blood sugar control was less stringent.

Now the federal researchers are publishing detailed data from that study for the first time. Researchers in the second study, from Australia and involving participants from 20 countries, are also publishing their results on blood sugar and cardiovascular disease. That study did not find an increase in deaths, but neither did it find any protection from cardiovascular disease with rigorous blood sugar control.

Thus both studies failed to confirm a dearly held hypothesis that people with Type 2 diabetes could be protected from cardiovascular disease if they strictly controlled their blood sugar.