First trial to test life-saving impact of lowering blood sugar finds increased death risk; rapid rate of reductions may be responsible
by Craig Weatherby
In one of the greatest surprises in recent medical history, a large US government study in mature adults with Type 2 diabetes found that lowering their blood sugar to the normal range actually increased their risk of death.
This seems to undermine the decades-old presumption that the chronically elevated blood sugar levels that characterize Type 2 diabetes raise the risk of premature death.
But these results may not exclude death-reduction benefits from lowering blood sugar. This was an exceptionally unhealthy group on multiple medications, and the large reductions in blood sugar achieved in the group that showed higher death rates may have been too rapid.
Here’s how the situation was described in a press release from the National Heart, Lung, and Blood Institute (NHLBI), which ran the trial (NHLBI 2008):
- “The ACCORD (Action to Control Cardiovascular Risk in Diabetes) study enrolled 10,251 participants. Of these, 257 in the intensive [blood-sugar-lowering] treatment group have died, compared with 203 within the standard treatment group.”
- “This is a difference of 54 deaths, or 3 per 1,000 participants each year, over an average of almost four years of treatment. The death rates in both groups were lower than seen in similar populations in other studies.”
According to NHLBI director Elizabeth G. Nabel, M.D., “A thorough review of the data shows that the medical treatment strategy of intensively reducing blood sugar below current clinical guidelines causes harm in these especially high-risk patients with type 2 diabetes. Though we have stopped this part of the trial, we will continue to care for these participants, who now will receive the less-intensive standard treatment” (NHLBI 2008).
In a press release, top NIH scientist Judith Fradkin, M.D. cautioned that “People with diabetes should never adjust their treatment plan or goals without consulting their health care providers.”
Researchers were quick to note that chronically elevated blood sugar definitely does cause several of major ills associated with chronically elevated blood sugar, including obesity, nerve damage, kidney disease, blindness and amputations.
We were surprised to learn that no one had ever conducted a large clinical trial to test the widely held medical belief that reducing blood sugar levels radically would reduce death risk among diabetics.
One reason for this failure was that researchers doubted that people like those in the study group—who had been diabetic for a decade with high blood sugar levels—could achieve and maintain normal blood sugar levels long enough to discover whether this would reduce death rates.
The participants were assigned randomly to one of three treatments: one comparing varying degrees of blood sugar control; another that compared varying degrees of cholesterol control; and a third that tested varying degrees of blood pressure control.
Some were taking four or five shots of insulin a day, or pills to lower their blood sugar in addition to other, unrelated medications.
No particular drugs or drug combinations could be linked to higher death risk, and no unusual cause of death was found, with most of the deaths from heart attacks.
The New York Times ran this cogent quote from Dr. Steven E. Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic: “It might be that patients suffered unintended consequences from taking so many drugs, which might interact in unexpected ways” (Kolata G 2008).
The Times’ Gina Kolata spoke with Irl Hirsch, M.D, a diabetes researcher at the University of Washington, who noted that lowering blood sugar very quickly in diabetes can worsen blood vessel disease in the eyes, while reducing levels more slowly protects them.
It could be that to some extent, the body adapts to chronically elevated blood sugar levels, and reacts badly to a rapid change in blood glucose levels.
To read our past coverage of nutritional factors affecting diabetes, search our newsletter archive.
- National Heart, Lung, and Blood Institute (NHLBI). For Safety, NHLBI Changes Intensive Blood Sugar Treatment Strategy in Clinical Trial of Diabetes and Cardiovascular Disease. February 6, 2008. Accessed online February 7, 2008 at http://public.nhlbi.nih.gov/newsroom/home/GetPressRelease.aspx?id=2551.
- Kolata G. Diabetes Study Partially Halted After Deaths. The New York Times, February 7, 2008. Accessed online February 7, 2008 at http://www.nytimes.com/2008/02/07/health/07diabetes.html