Simple Saliva Swab and Early HbA1c Test Predict Diabetes

Becky McCall

February 11, 2014

A new saliva test and earlier use of the HbA1c blood test could pick up type 2 diabetes in high-risk patients earlier than methods in current use, show data from 2 studies.

Both tests could both provide an effective and timelier means of disease detection, precipitating earlier intervention, say the respective researchers.

The first study identifies 1,5 anhydroglucitol (1,5- AG) in the saliva of patients as a possible marker of type 2 diabetes and was carried out by researchers from Weill Cornell Medical College in Qatar (WCMC-Q) and published online last month in the Journal of Clinical Endocrinology and Metabolism.

The second, on earlier use of the HbA1c test, was published online in November 2013 in the European Journal of General Practice by Nataly Lerner, MD, from the Sackler Faculty of Medicine, Tel Aviv University, Israel, and colleagues.

Saliva Test Could Be Screening Tool for Diabetes

Senior author Karsten Suhre, PhD, and colleagues examined a total of 2178 metabolites in saliva, blood plasma, and urine sourced from 188 participants already diagnosed with type 2 diabetes and 181 undiagnosed controls, all of whom were of Arab or Asian heritage.

A strong association of type 2 diabetes with 1,5-AG in saliva (P < .001) was identified, with saliva 1,5-AG levels showing a high correlation with 1,5-AG levels in the blood and inversely correlated with blood glucose and HbA1c levels.

The study, which was conducted in Qatar, included Arab, South Asian, and Filipino participants, and the findings were found to be consistent across all racial groups, irrespective of body mass index (BMI), age, or gender.

The data suggest 1,5-AG in saliva constitutes a noninvasive marker for deregulated short-term glycemic control, which "can be especially useful as a screening tool for undetected type 2 diabetes," they write.

Dr. Suhre noted the importance of detecting type 2 diabetes early in these populations to facilitate timely intervention with appropriate medication, noting that Middle Eastern populations had exceptionally high diabetes rates overall and especially among the young. He added that the saliva test would be one way of expediting speedy diagnosis and treatment.

"Diabetes is a really vicious disease, as initially when you get it you don't feel any different; you can live for years without knowing about it, but if you don't adapt your lifestyle you're slowly but continuously destroying your body," he said in a statement. "It's like running an engine using the wrong kind of oil."

The researchers suggest a potential use of the saliva test in children or other patients averse to blood sampling and possible use in a national screening program or dental setting.

Risk for Diabetes Doubles With Each 0.5%-Point Increase in HbA1c

In the other study, Dr. Lerner and colleagues show that the HbA1c blood test reveals an individual's risk of developing type 2 diabetes at a stage far earlier than previously thought possible. Used in combination with information such as family history, poor diet, lack of exercise, and obesity, the test could help doctors provide earlier treatment.

The participants were part of a community-based historic cohort of 10,201 patients undiagnosed with type 2 diabetes who received an HbA1c test during the years 2002–2005. Data on diabetes risk factors and the onset of disease over a 5-8 year follow-up period were then retrieved.

After the follow-up period, the researchers found that individuals with HbA1c levels above 5.5% but below 6.5% had an increased risk of developing type 2 diabetes. Furthermore, HbA1c had a stronger correlation with increased likelihood of diabetes than other risk factors investigated, including age and low socioeconomic status. The risk of developing diabetes doubled with every increase of 0.5% in HbA1c level, the authors note.

This study supports other recently published findings showing a benefit in closely following individuals with HbA1c levels in the range of 5.5% to 6.5%, they say.

"Our study supports the idea that the HbA1c test, used to diagnose type 2 diabetes, can also be used at a much earlier stage to screen for the disease in the high-risk population, like overweight patients," says Dr. Lerner in a statement.

The HbA1c test features in the guidelines of the American Diabetes Association (ADA) and World Health Organization as a criterion for diagnosing type 2 diabetes. According to the ADA, having an HbA1c level of 6.5% or greater is an indicator of type 2 diabetes and a level of between 5.7% and 6.4% is an indicator of prediabetes.

In conclusion, the authors suggest "HbA1c testing of patients at risk of developing diabetes (for example, according to BMI and history of cardiovascular disease) to promote stratification of a target population for disease prevention and early diagnosis."

Dr. Suhre and colleagues and Dr. Lerner and colleagues have reported no relevant financial relationships.

J Clin Endocrinol Metab. Published online January 1, 2014. Abstract

Eur J Gen Pract . Published online November 29, 2013. Abstract

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