Medical Device Daily Executive Editor
SAN DIEGO – Tight glucose control is widely known to lower cardiovascular disease (CVD) risk in Type 2 diabetics. Now, the same can be said for Type 1 diabetics, those who require daily intake of insulin via injection, inhalation or pumps.
Results of a follow-up study to the landmark Diabetes Control and Complications Trial (DCCT), reported Sunday during a “Late-Breaking Clinical Trials” session at the 65th scientific sessions of the American Diabetes Association (ADA; Alexandria, Virginia), were characterized by the ADA’s top scientific official as “the biggest news story of this meeting.”
During a mid-day press conference held prior to the presentation of results of the Epidemiology of Diabetes Interventions and Complications (EPIC) study, Richard Kahn, PhD, the association’s chief scientific and medical officer, said it was “remarkable to see this kind of substantial reduction [in CVD rates] after just six years of intensive therapy.”
The EDIC research was a follow-up to the epic DCCT study, which compared intensive management of blood glucose to conventional control in 1,441 persons with Type 1 diabetes.
DCCT and EDIC were funded by the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health (NIH; both Bethesda, Maryland).
The original study, which ran from 1983-1993, involved intensive treatment through at least three insulin injections a day, or via an insulin pump. “Intensive” meant keeping hemoglobin A1c (HbA1c) as close as possible to what is considered “normal” – 6% or less.
The HbA1c blood test reflects a person’s average blood sugar over a two- to three-month period and is a key diagnostic used in determining both control and compliance by both Type 1 and Type 2 diabetics.
David Nathan, MD, of Massachusetts General Hospital (Boston), who co-chaired the DCCT/EDIC research group, noted that the original DCCT study focused on eye, nerve and kidney damage of Type 1 diabetes, finding that intensive glucose control “greatly reduced” such effects.
A study of DCCT participants published in 2003 showed that tight control also lowers the risk of atherosclerosis.
The EDIC study focused on such cardiovascular events as angina, heart attack and stroke, with the most remarkable finding being the long-lasting benefit of such control.
In a statement, EDIC chair Saul Geneth, MS, of Case Western Reserve University, said, “The longer we follow patients, the more we’re impressed by the lasting benefits of tight glucose control.” He said that the earlier such therapy begins and the longer it is maintained, “the better the chances of reducing the debilitating complications of diabetes.”
The results reported at the late-breaking trials session indicate that the intensively treated patients among the roughly 1,375 persons who volunteered to continue in the study while continuing intensive therapy on their own have had less than half the number of CVD events – 46 vs. 98 – than the conventionally treated group.
Noting that the risk of heart disease is “about 10 times higher in people with Type 1 diabetes than in people without diabetes,” a proportion which he termed “much higher than in the Type 2 population.” Nathan added that tight control “is difficult to achieve and maintain, but its advantages are huge.”
He said during the press conference that “the major message” of the EDIC study after some 6-1/2 years of follow-up “is that intensive therapy should be implemented in as many Type 1 patients as possible, and as early as possible.”
Such patients, Nathan added, “get a remarkably durable benefit from intensive therapy – clearly, intensive therapy is important.” And that benefit is as substantial as it is long-lasting. “For every 10% lower A1c, patients get a 21% reduction in heart disease.”
In citing the “enormous reductions” in cardiovascular events reported by the EDIC study group, the ADA’s Kahn said: “All of this makes it a ‘wow’ event that will have people talking about these results in the hallways through the rest of this meeting.”
In a second study whose results were reported during the late-breaking trials session, researchers said that diabetic retinopathy lesions were found in nearly 8% of pre-diabetic participants in the Diabetes Prevention Program, as well as in 12% of Type 2 diabetics who advanced to a diagnosis of diabetes during the DPP.
Richard Hamman, MD, professor and chairman of the department of preventive medicine and biometrics at the University of Colorado School of Medicine (Denver) and vice chairman of the DPP, said the study findings “suggest that retinopathy begins to show very early in diabetes.”
Noting that “certain retinopathy lesions are considered indicative of the presence of diabetes because they are the first retinal changes to develop in this disease,” he said the early study findings “suggest that changes in the eye may be starting earlier and at lower glucose levels than we previously thought.”
Hamman said the eye changes found in pre-diabetics “may lead diabetes experts to reconsider the diagnostic thresholds used to define diabetes, which are based on levels of blood glucose.”
Mass General’s Nathan, who chaired the DPP study, said the study findings were based on a small, random sample of study participants – about 12% of total trial participants. “These initial findings confirm what other studies have suggested,” he said. “The complications of diabetes may begin before diabetes is diagnosed, at least by current-day standards.”
He said that an expanded study of the remaining DPP outcome study participants “might enable us to establish more appropriate diagnostic thresholds.” Noting that the early findings “suggest that retinopathy begins to show very early in diabetes,” Hamman said: “A good retinal exam, as a patient transitions from pre-diabetes to diabetes, is important.”
He added, “Some of these lesions are beginning to show at very low levels of pre-diabetes.” In order to slow the development of retinopathy, he said, “we have to start intensive [glucose control] therapy much earlier.”
Emily Chew, MD, of the National Eye Institute, the NIH unit that funded the study, said, “These findings reinforce the recommendation that patients with newly diagnosed Type 2 diabetes should be screened for retinopathy.”