"We know that having diabetes may be associated with an increased risk of having a first stroke," said study author Dr. Moon-Ku Han, of Seoul National University College of Medicine. "But our results indicate that there is an optimal blood sugar level that may start to minimize the risk of having another stroke, a heart attack or other vascular problems, and it's right in the 6.8% to 7% range."
The study included more than 18,500 people with diabetes (average age: 70) who were admitted to the hospital for an ischemic stroke -- one caused by a blood clot.
Participants had an average A1C of 7.5%. Anything above 6.5% typically shows diabetes, while levels below 5.7% are considered normal.
A year later, researchers found that 1,437 participants, about 8%, had experienced a heart attack or died from vascular disease. About 5% (954) had another stroke.
The study found participants' risk for a heart attack or similar vascular diseases was 27% greater when they were admitted to the hospital with A1C levels above 7%, compared to those admitted with A1C levels below 6.5%. Their risk for stroke was 28% greater when admitted with A1C levels above 7%, compared to those below 6.5%.
The findings were published online Sept. 29 in the journal Neurology.
"Our findings highlight the importance of keeping a close eye on your blood sugar if you're diabetic and have had a stroke," Han said in a journal news release.
Researchers noted that one limitation of the study is that blood sugar levels were only tested at the outset.
The American Diabetes Association has more on living with diabetes.
SOURCE: American Academy of Neurology, news release, Sept. 29, 2021