Closely controlling blood sugar levels early in the treatment of type 1 diabetes was linked to a lower risk of death later in life, according to findings from a study that followed people with type 1 diabetes for approximately 27 years. The findings were published in the January 6 issue of JAMA.
"The outlook for people with type 1 diabetes continues to improve," said Catherine Cowie, PhD, of NIH's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which funded the study. "These results show that by tightly controlling their blood glucose, people with type 1 diabetes can live longer," Dr. Cowie said.
The study authors examined data from a 1983-1993 study of 1,441 healthy volunteers with type 1 diabetes (ages 13 to 39 years) who were given either intensive treatment designed to bring blood sugar levels as close to normal as possible, or conventional treatment that was designed to avoid the symptoms of high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia). At the beginning of the study—known as the Diabetes Control and Complications Trial (DCCT)—none of the participants had complications of diabetes, such as heart disease or eye, nerve, or kidney disease.
Intensive therapy was linked to lower blood sugar level (hemoglobin A1c) compared with conventional treatment (7% vs 9%). In addition, people given intensive therapy had lower rates of eye, kidney, and nerve disease. Because of these positive findings, all study participants were taught intensive blood glucose control at the end of the study.
A total of 1,394 people in the original study were entered into a second study—called the Epidemiology of Diabetes Control and Complications (EDIC) trial—that followed patients from 1994 to 2012. This study showed no difference in blood sugar control after 5 years (A1c was approximately 8% in both groups).
Intensive Treatment Lowers Death Risk by 33%
Over approximately 27 years, 107 people died—43 (40.2%) in the group that originally received intensive treatment and 64 (59.8%) in the group that originally received conventional treatment. This difference means that the intensive group had a 33% reduced risk of death.
The risk of death was 56% higher in patients with high blood sugar levels and more than 2 times higher in patients with albuminuria (too much protein in their urine, which is a sign of kidney disease).
The findings "complete our knowledge about the benefits of intensive therapy of type 1 diabetes designed to get the hemoglobin A1c to or below 7%. We have previously shown that this dramatically reduces the chances of developing eye, nerve, kidney and heart disease, and now it has been shown to reduce early mortality," said lead author Trevor Orchard MD, Professor of Epidemiology, Medicine, and Pediatrics at the University of Pittsburgh Graduate School of Public Health. "Taken with other data it now seems most individuals with type 1 diabetes can expect a normal life expectancy," Dr. Orchard added.
"These results further emphasize the importance of good early glucose control, as this reduces the risk for increased protein in the urine in general, as well as diabetic kidney disease," Dr. Orchard said.
"Important though these results are, individuals should also keep their blood pressure and blood fats under control!," Dr. Orchard added.
February 12, 2015
Writing Group for the DCCT/EDIC Research Group, Orchard TJ, Nathan DM, et al. Association between 7 years of intensive treatment of type 1 diabetes and long-term mortality. JAMA. 2015;313(1):45-53.
The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med. 1993;329(14):977-986.
Nathan DM, Bayless M, Cleary P, et al. DCCT/EDIC Research Group. Diabetes control and complications trial/epidemiology of diabetes interventions and complications study at 30 years: advances and contributions. Diabetes. 2013;62(12):3976-3986.