A recent question from a correspondent prompted me to look carefully at the largest and longest study of people with type 2 diabetes. The United Kingdom Prospective Diabetes Study or UKPDS compared conventional and intensive therapy in more than 5,000 newly diagnosed people with type 2 diabetes.
What…is the normal level?
This research project followed the results of different therapies for 10 years with the conclusions reported in numerous articles in professional publications since 1998. It parallels the earlier and better known study of people with type 1 diabetes known as the Diabetes Control and Complications Trial (DCCT).
My questioner was Kenneth G. Andersen, D.C., a chiropractor practicing in Bakersfield, California. "I was diagnosed last Friday with type 2 diabetes," he wrote. "Needless to say I am somewhat scared. I have a question that I have not been able to find an answer to."
"If a type 2 patient can control his blood sugars by diet, exercise, and weight loss—which I hope to be able to do—can he prevent the adverse secondary effects of the disease such as blindness and neuropathy? Or can he just delay the inevitable?"
Dr. Andersen's question has to be one that is somewhere in the minds of everyone with diabetes. It asks essentially whether we can avoid the complications of diabetes through intensive control.
The UKPDS went further to giving us an answer to this key question than any research before or since. The main conclusion of the Diabetes Trials Unit, which sponsored the study, was that "complications of type 2 diabetes are not an inevitable outcome of a chronic disease and...the risk can be reduced by appropriate therapy."
It studied the results not only of better blood glucose control but also better blood pressure control. It found that better blood glucose control reduced the risks of major diabetic eye disease by a quarter and early kidney damage by a third. Better blood pressure control among those whose blood pressure was high reduced the risks of death from long-term complications of diabetes by a third, strokes by more than a third, and serious deterioration of vision by more than a third.
By better blood glucose control the UKPDS meant reducing the average Hemoglobin A1c from 7.9 percent to 7.0 percent. For them, 7.0 percent meant tight control.
The study showed that the risk of complications dropped 35 percent for every percentage point decrease in Hemoglobin A1c, according to the American Diabetes Association position statement on the Implications of the United Kingdom Prospective Diabetes Study reported in the January 2002 issue of Diabetes Care. The most hopeful statement to my mind was, "There was no evidence of any glycemic threshold for any of the microvascular complications above normal glucose levels."
What does the study say is the normal level? A Hemoglobin A1c of 6.2 percent.
The UKPDS calls a Hemoglobin A1c result of 7.0 percent "tight control," and does not directly address what keeping it within normal range would do. But the implication is that full normalization of blood glucose could totally prevent these complications.
The American Diabetes Association originally published this article on its Web site as one of my “About the Internet” columns.
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