Strictly controlling blood glucose levels in type 2 diabetics with long-term, serious coexisting health problems such as heart disease and hypertension does not lower their risk of a heart attack or stroke, according to a UC Irvine Health Policy Research Institute study.
Researchers did find, however, that firm glucose control -- defined as keeping hemoglobin levels, or A1C, below 7 percent -- may reduce cardiovascular issues for diabetics with fewer and less severe health problems.
Study co-leader Dr. Sheldon Greenfield, Donald Bren Professor of Medicine at UCI and co-executive director of the Health Policy Research Institute, said the findings -- coupled with prior research -- suggest that guideline developers and physicians should account for a patient's other conditions in determining diabetic treatment goals. An earlier federal study found that lowering blood sugar too quickly or too much could harm or even kill some diabetics.
"We believe that in certain cases doctors should aim for just moderate blood glucose levels and aggressively treat coexisting conditions," said Greenfield.
Study co-leader Sherrie Kaplan, associate dean at UCI's School of Medicine, said the results help explain inconsistencies in previous studies on whether an under-7 A1C decreases heart attack and stroke risk in diabetics. Some have shown that it does, and some have indicated no such link.
"The findings reveal that strict glucose control benefits some patients but not others depending on certain factors, mainly concurrent illnesses," said Kaplan, co-executive director of the Health Policy Research Institute. "They also raise serious questions about guidelines advocating a single approach for all diabetics."
Study results appear in the Dec. 15 issue of Annals of Internal Medicine.
The authors reviewed data from 2,613 patients with type 2 diabetes under the care of 205 physicians in Italy. They analyzed histories of heart disease, lung disease, heart failure, urinary tract disease, arthritis, foot issues and digestive conditions and -- based on a summary score -- classified the diabetics as having either low to moderate or high levels of other health problems. Researchers then followed the patients -- whose blood sugar levels were strictly controlled -- for about five years to see which ones experienced heart attacks or strokes.
In addition to Greenfield and Kaplan, John Billimek of UCI and Fabio Pellegrini, Monica Franciosi, Giorgia De Berardis and Dr. Antonio Nicolucci of the Consorzio Mario Negri Sud in Santa Maria Imbaro, Italy, participated in the study, which was funded by Pfizer of Italy.
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