Effect of Intensive Therapy for Type 1 Diabetes

Results of an observational study showed a modest reduction in the rate of all-cause mortality after a mean of 27 years in patients with type 1 diabetes treated with initial intensive diabetic therapy compared to those treated with conventional therapy [JAMA. 2015;313(1):45-53].

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The observational study included participants from the DCCT [Diabetes Control and Complications Trial] cohort and the follow-up observational study, EDIC [Epidemiology of Diabetes Control and Complications]. In DCCT, 1441 patients with type 1 diabetes who were 13 to 39 years of age were randomized to intensive therapy (ie, goal of achieving glycemia as close to the nondiabetic range as possible; n=711) or conventional therapy (ie, goal of avoiding symptomatic hypoglycemia and hyperglycemia; n=730). The study took place between 1983 and 1993, and patients were included for a mean of 6.5 years.

Patients were excluded from the study if they had a history of cardiovascular disease (CVD), hypertension, or hypercholesterolemia.

At the end of the trial, 97% of the DCCT cohort (n=1394) entered the EDIC observational study in which they continued intensive therapy controlled by their personal physicians.

According to Trevor J. Orchard, MD, professor of epidemiology, medicine, and pediatrics, department of epidemiology, GSPH, University of Pittsburgh, Pennsylvania, an investigator of the studies, previous results from these trials have shown that lowering glycated hemoglobin (HbA1c) to levels of <7% dramatically reduced the chance of developing morbidities associated with type 1 diabetes, including eye, nerve, kidney, and heart disease.

The current observational study was carried out in order to follow the patients from DCCT and EDIC to determine whether mortality differed between patients treated by intensive diabetic therapy or conventional therapy over long-term follow-up (1994 to December 2012).

Over 27 years of mean follow-up, data were available on 1429 participants (99.2%). A total of 107 patients died—43 in the intensive treatment group and 64 in the conventional group. The primary causes of death were CVD (n=24), cancer (n=21), acute diabetes complications (n=19), and accidents/suicide (n=18). Patients who received intensive treatment had a lower all-cause mortality risk (hazard ratio [HR], 0.67; 95% confidence interval [CI], 0.46-0.99; P=.04). The absolute risk reduction was small at –109 per 100,000 patient-years (95% CI, –218-–1). The study found that all-cause mortality was significantly associated with higher levels of HbA1c (HR, 1.56; 95% CI, 1.35-1.81 per 10% relative increase in HbA1c; P<.001), as well as the development of albuminuria (HR, 2.2; 95% CI, 1.46-3.31; P<.001).

“These latest results complete our knowledge about the benefits of intensive therapy of type 1 diabetes designed to get HbA1c to or below 7%,” said Dr. Orchard in an interview with First Report Managed Care, adding that new evidence has shown that early mortality, as well as morbidity, is reduced with intensive therapy. “Taken with other data, it now seems most
individuals with type 1 diabetes can expect a normal life expectancy.”

Limitations of the study included the initial selection of patients with a lower CVD risk and the lack of analyses of the potential effect of cardioprotective medication use on outcomes.—Mary Beth Nierengarten