A report from the EDIC group in 2002 found that the people from the intensive treatment arm of the DCCT still had a 62% reduction in the risk of retinopathy seven years after the end of the DCCT. Long-term results for nephropathy were published in 2003, covering eight years of follow-up, and members of the intensive treatment group still enjoyed a 59% reduction in the risk of microalbuminuria. More striking still, that group saw an 84% reduction in the risk of developing clinical albuminuria, a more advanced stage of kidney disease. The latest data for neuropathy were published in 2006, and showed that eight years after the DCCT ended, the participants who had been on intensive treatment experienced a 64% reduction in the risk of neuropathy.
The DCCT studied Type 1 diabetes, but the vast majority of cases of diabetes are Type 2. However, the value of intensive therapy was demonstrated for Type 2 diabetes by the United Kingdom Prospective Diabetes Study (UKPDS), published in 1998. The UKPDS covered a 20-year period and included more than 5,100 people with Type 2 diabetes in England, Northern Ireland, and Scotland.
The UKPDS showed that intensive treatment of Type 2 diabetes, using sulfonylurea drugs (oral medicines that increase the secretion of insulin by the pancreas) or insulin, reduced microvascular complications (primarily retinopathy and nephropathy) by 25%. Another group of people in the study who were overweight and received intensive treatment with metformin (an oral medicine that suppresses glucose production by the liver and enhances the body’s sensitivity to insulin) saw a 32% decrease in diabetes complications.
Where are we now?
Despite the overwhelming evidence of the importance of “tight” blood glucose control in people with Type 1 and Type 2 diabetes, it is still far from the norm. In a study published in the January/February 2006 issue of Annals of Family Medicine, Dr. Stephen J. Spann and his colleagues reported on a review of charts of people with Type 2 diabetes from four large primary-care-based research networks. They found that only 40.5% of these people had HbA1c values below 7%. Moreover, 31.3% of HbA1c values were above 8%.
These findings echo those of the National Health and Nutrition Examination Survey (NHANES) from 1999–2000, in which only 37% of participants were found to have achieved the target goal of an HbA1c level less than 7%. Another 37.2% of the participants had an HbA1c above 8%. It is notable that these percentages did not change significantly from the earlier NHANES covering 1988–1994.
Not even a majority of people who get their diabetes care in specialized clinics at academic medical centers are reaching target HbA1c values. A 2002 review from 30 academic medical centers in the United States found that while nearly all patients with Type 1 or Type 2 diabetes had received an HbA1c test within the previous year, only 34% were at 7% or less.
“The reason we did our study,” said Dr. Spann, who is Chairman of Family and Community Medicine at Baylor College of Medicine in Houston, Texas, “is that while we understand that improved glycemic control is better, we struggle with how to make it happen in primary care. We wondered what we could learn about elements that might predict good glycemic control.”
“We didn’t really find anything that was absolutely predictive of good control,” he said. “We did learn that the level of complexity rises as you start adding the other important treatment targets, such as blood pressure and cholesterol. It’s hard enough to hit one target, and even harder to achieve targets simultaneously for multiple risk factors.”