TUESDAY, Aug. 12 (HealthDay News) -- Earlier onset, longer duration and greater severity of diabetes may increase the risk for mild cognitive impairment, according to Mayo Clinic researchers.

Previous research identified a link between mild cognitive impairment and diabetes. Poor blood glucose (sugar) control over a long period of time may lead to a loss of brain cells, according to background information in a news release about the study.

In addition, diabetes is associated with cardiovascular disease risk and stroke, which may increase the risk of cognitive impairment.

This new study of people ages 70 to 89 found that rates of diabetes were similar among 329 participants with mild cognitive impairment (20.1 percent) and 1,640 participants without mild cognitive impairment (17.7 percent).

However, the researchers found an association between mild cognitive impairment and developing diabetes before age 65, having diabetes for 10 years or longer, being treated with insulin, and having diabetes-related complications.

The findings were published in the August issue of the journal Archives of Neurology.

"Severe diabetes mellitus is more likely to be associated with chronic hyperglycemia [high blood glucose], which, in turn, increases the likelihood of cerebral microvascular disease and may contribute to neuronal damage, brain atrophy and cognitive impairment," the study authors wrote.

They said the fact that people with the eye disease diabetic retinopathy were twice as likely to have mild cognitive impairment supports the theory that diabetes-related damage to blood vessels in the brain may contribute to the development of cognitive problems.

"Our findings suggest that diabetes mellitus duration and severity, as measured by type of treatment and the presence of diabetes mellitus complications, may be important in the pathogenesis of cognitive impairment in subjects with diabetes mellitus," the Mayo researchers concluded. "In contrast, late onset of diabetes mellitus, short duration of diabetes mellitus or well-controlled diabetes mellitus may have a lesser effect."

More information

The Alzheimer's Association has more about mild cognitive impairment  .

THURSDAY, Aug. 7 (HealthDay News) -- A widely used test to monitor blood sugar levels in people with diabetes could help identify millions of people with undetected diabetes, according to a consensus statement released by a team of experts.

The hemoglobin A1c test (HbA1c) shows how much glucose red blood cells have been exposed to in the previous 120 days, the average life span of the cells.

"The test is a measure of long-term glucose control, but doctors don't typically use it to screen for or diagnose the disease. There's reason to believe it could help identify many of the estimated six million people in the U.S. who have diabetes but don't know it," Dr. Christopher Saudek, director of the Johns Hopkins Comprehensive Diabetes Center in Baltimore, said in a Hopkins news release.

Current screening and diagnostic tests measure only the amount of sugar present at the moment the blood sample is taken, which means the tests are accurate only if patients fast for at least 10 hours prior to the test. Even if a patient does fast that long, the test can still miss people who have diabetes or are at high risk for the disease. That's because glucose also varies depending on a person's diet and level of exercise for several days before they provide a blood sample.

"If a patient is scheduled for a physical, he or she may 'tune up' by changing their regimen for a few days and throw off their test results, causing doctors to miss the patient's usual pattern of high blood sugar," said Saudek, who is also a professor of endocrinology and metabolism at the Johns Hopkins University School of Medicine.

In the consensus statement, Saudek and colleagues conclude that the HbA1c test should be used as front-line method for identifying patients with diabetes, especially people at high risk for the disease. The HbA1c test doesn't require fasting and isn't affected by short-term changes in diet and exercise.

The consensus, published in the July issue of The Journal of Clinical Endocrinology & Metabolism, was reached by the experts at a meeting financially supported by Metrika Inc., a manufacturer of diabetes testing equipment.

More information

The U.S. National Diabetes Information Clearinghouse has more about diabetes.

WEDNESDAY, July 30 (HealthDay News)-- Women who develop diabetes before they become pregnant are three to four times more likely than non-diabetic women to have a baby with at least one birth defect, says a U.S. Centers for Disease Control and Prevention study.

This is the first study to identify the wide range of birth defects -- such as heart defects, brain and spine defects, oral clefts, limb deficiencies, and defects of the kidneys and gastrointestinal tract -- associated with pre-pregnancy diagnoses of type 1 or type 2 diabetes.

The study was published in the American Journal of Obstetrics & Gynecology.

"The continued association of diabetes with a number of birth defects highlights the importance of increasing the number of women who receive the best possible preconception care, especially for those diagnosed with diabetes," lead author Dr. Adolfo Correa, an epidemiologist at the CDC's National Center on Birth Defects and Developmental Disabilities, said in a CDC news release.

"Early and effective management of diabetes for pregnant women is critical in helping to not only prevent birth defects, but also to reduce the risk for other health complications for them and their children," Correa addedd.

In addition, preconception care should be considered and promoted for women with pre-pregnancy obesity, which is a known risk factor for both diabetes and birth defects, Correa and colleagues recommended.

For this study, the researchers analyzed data on more than 30,000 people seen at nine birth defects centers across the country.

Birth defects affect one in 33 infants and are a leading cause of infant death, according to background information in the CDC news release. While risk factors for some birth defects have been identified, the cause of most birth defects is unknown.

More information

The Nemours Foundation has more about birth defects  .