''This study clearly demonstrates and documents that there can be a large number of people who can go a very, very long time with type 1 diabetes and not suffer with dire complications," says researcher George L. King, MD, chief scientific officer at Joslin Diabetes Center and professor of medicine at Harvard Medical School.
The study is published in Diabetes Care.
Explaining why is not simple, however. In the study, being free or nearly free of complications didn't correlate directly with control of blood sugar, King says.
He isn't discounting the importance of blood sugar control. It's shown to reduce the risk of complications. However, his study suggests other mechanisms may help explain the protection from complications he found in some.
Protection From Diabetes Complications
King studied 351 so-called medalists who had received medals from Joslin Diabetes Center after living with type 1 diabetes for 50 years. In type 1 diabetes, the pancreas does not produce adequate insulin to control blood sugar. In type 2 diabetes, the body may not produce enough insulin or insulin resistance occurs where the body does not respond normally to insulin.
Insulin moves glucose into the cells, where it's used for energy.
The participants' average age was nearly 68. They were about 11 at the time of diagnosis.
King's team looked at common complications, including eye problems known as retinopathy, nerve problems or neuropathies, kidney problems or nephropathies, and cardiovascular disease.
They found that:
- 43% did not have advanced diabetic eye complications.
- 87% were free of kidney disease.
- 39% did not have nerve disease.
- 52% did not have cardiovascular disease.
''Overall, about 20% do not have any eye, kidney, or nerve disease," King tells WebMD.
Role of Proteins
King's team evaluated blood sugar levels in the participants. On average, blood sugar levels were under good control. The average hemoglobin A1c test, a reflection of blood sugar levels over the past three months or so, was 7.3%. Experts often recommend those with diabetes keep A1c at 7% or below.
But the blood sugar levels did not correlate with the lower complication rates.
To find another explanation, the researchers also evaluated a family of proteins known as advanced glycation end products (AGEs). These are increased by high blood sugar levels.
Those who had high levels of two specific AGEs were more than seven times as likely to have a complication.
Then came a surprise, King says. People with other combinations of some of the AGEs measured were actually protected from eye complications.
It suggests some AGE combinations may not be as toxic as believed, King says, and may actually be protective.
''Some AGEs may be processed differently in different people, and those differences may account for the protection," he says.
Those with diabetes who are free or mostly free of complications ''are leading a charmed life," says Aaron Vinik, MD, PhD, director of research and neuroendocrine unit at Eastern Virginia Medical School's Strelitz Diabetes Center.
He speculates that those who escape complications may have developed good defensive mechanisms against these AGEs over the years, among other explanations. These defense mechanisms somehow make their AGEs less toxic.
The diabetes veterans in the study, Vinik says, "really took care of themselves." Less was known about diabetes care when they were diagnosed, he says. Doctors were not even talking about tight control of blood sugar then.
Learning more about those with diabetes who escape the complications, King says, may eventually help researchers intervene in those prone to complications.
For now, those with diabetes hoping to avoid complications can take a page from the medalists' book, King says.
''Most do fairly rigorous exercise at least three times a week, 45 minutes or more," he says.
Their attitude is positive, King tells WebMD. They're not in denial about their disease and the need to control it.