June 7, 2004 (Orlando, Fla.) -- For people with type 1 diabetes, being aggressive about their blood sugar control can have significant benefits for years to come, suggests a new study. And the same appears true for type 2 diabetes.
Completed in 1994, the landmark Diabetes Control and Complications Trial (DCCT) showed that people with type 1 diabetes who are aggressive about managing their diabetes -- checking blood sugar four to five times a day or more and multiple daily insulin injections -- have much lower rates of eye, heart, kidney, and nerve problems than people who take insulin only once or twice a day.
Now, a new study that continued to follow the DCCT participants shows that eight years after the study ended, patients who maintained tight blood sugar control during the study had significantly less damage to their nerves, eyes, and kidneys.
Interestingly, the benefits for early intensive therapy held up even though patients receiving conventional treatment were given a crash course in intensive diabetes management at the end of the DCCT, and practiced tight blood sugar control after that.
In addition, patients in the intensive treatment group in DCCT saw later benefits from their early efforts even though they gradually began to lose the good blood sugar control they had originally achieved.
Results of the new study were presented at the annual scientific meeting of the American Diabetes Association.
"We don't yet know how long this trend is going to last. I think we were all stunned when we started seeing these trends that the [blood sugar levels] are predictive [of protection against disease] early in the game," co-researcher Catherine L. Martin, MS, APRN, clinical care coordinator at the Michigan Diabetes Research and Training Center at the University of Michigan in Ann Arbor, tells WebMD.
Tight Blood Sugar Control Leads to Less Damage
The new trial enrolled nearly 1,400 patients with type 1 diabetes, 96% of the original subjects in the DCCT study. Patients were evaluated annually using a special questionnaire and a foot examination looking for nerve damage common with diabetes.
At the end of the DCCT, the researchers found that blood sugar levels were significantly different between the two groups. But by the end of eight years into the new study they were nearly identical. This is, in part, due to a loss of blood sugar control in the former intensive control group, but also improved efforts on part of the conventional treatment patients, say the researchers.
"I think some of the convergence is due to a withdrawal of the intensity with which we follow people up. In DCCT, people were provided with all their supplies, they got weekly phone calls, they got monthly visits. Now care has been turned over to others and that intensity of follow-up does not exist, and so I think we've seen a regression to the [average]," says Martin.
Despite the gradual loss of blood sugar control among those in the intensive therapy group, the investigators found that those patients were still 36% to 50% (depending on the test used) less likely to develop diabetic nerve damage. Similar protective benefits were seen for eye and kidney disease, Martin says.
Rury T. Holman, MD, professor of diabetic medicine at the University of Oxford in England, was not involved in the study but saw similar results among patients with type 2 diabetes as co-chair of the United Kingdom Prospective Diabetes Study (UKPDS).
Holman tells WebMD that while the benefits of tight blood sugar control are well known, the durability of the effect comes as a surprise.
"What we see is the same as we saw in the type 2 patients in UKPDS, which is there seems to be a continued protection from risk," Holman says. "It probably takes a considerable amount of time for those benefits to be lost. What's interesting today is that they're still seeing it at seven and eight years."