Three decades ago, the landmark Diabetes Control and Complications Study was just beginning. To mark the anniversary of the most important advancement in diabetes care in most of our lifetimes, I've been recalling how the study came about and what it revealed. In short, the DCCT proved the tight control of type 1 diabetes not only was an achievable goal, but that it prevented or delayed complications.

But there are questions left. For example, what did the study actually prove? The journal Diabetes Care paid tribute to the anniversary in its January issue, and it summarized the central findings in six points, which are quoted (with commentary) below.