Thirty Years Wiser: How the DCCT trial continues to nurture the landscape of type 1 diabetes science

In 1983, a trial began that would forever alter the standard of management of type 1 diabetes (T1D) and serve as a stepping stone to future research advances—and as we mark the 30th anniversary of the trial’s inception, we are still learning from the study.

The Diabetes Control and Complications Trial (DCCT), a 10-year multicenter clinical trial, studied 1,441 people with T1D for an average of 6.5 years each, to examine whether intensive versus conventional methods of blood-glucose control could affect one’s development of dangerous diabetes complications. In 1993, staggering results from the trial proved that intensive therapy—where participants kept their HbA1c levels as close to normal as possible through frequent monitoring and insulin injections—reduces the risk of complications such as diabetic kidney, eye, and nerve disease by 35-76 percent, compared with what was then considered conventional treatment of one or two insulin injections daily and one urine or blood glucose test per day.

The DCCT is credited for spurring a change in the way diabetes is managed. But its effects did not end there. Most of the participants of the DCCT volunteered for the follow-up study beginning in 1994, called the Epidemiology of Diabetes Interventions and Complications (EDIC) study. This subsequent research has continued to uncover insights that could impact people with T1D today.

In 2002-2003, EDIC researchers determined that the period of intensive glucose control during the DCCT continued to reduce the risk of microvascular complications 7-8 years later, despite comparable glucose control between the two groups of participants after the initial study. Coined “metabolic memory,” this phenomenon suggests that implementing intensive glucose control as early as possible could help reduce the risk of complications down the line.

In 2005, EDIC researchers reported another interesting statistic: DCCT participants who had undergone intensive treatment during the study had fewer than half the number of cardiovascular complications compared with those treated conventionally, throughout an average of 17 years since their enrollment in the DCCT. For the first time, research showed that intensive glucose control could have long-term benefits for reducing heart attacks, strokes, and cardiovascular-related death in people with T1D.

New insights into hypoglycemia and the genetics of diabetes complications are also forming from the base of data that the DCCT study provided 30 years ago. These studies and future ones highlight the importance of a strong investment in long-term research—an investment that has been made possible through funding from organizations like JDRF, and with governmental support through the Special Diabetes Program (SDP), which makes up roughly one-third of U.S. government support for T1D research.

As advocates of T1D research, we can help protect and increase critical funding through JDRF and the SDP, so that long-term studies have the resources needed to continue revealing information that could improve and save lives. In addition to advocacy, people with T1D and their families can help research advance by participating in clinical trials. For more information, visit the JDRF Clinical Trials Connection website: