Non-fasting blood test can screen youth for prediabetes

A simple blood test that does not require overnight fasting has been found to be an accurate screening tool for identifying youth at risk for type 2 diabetes and heart disease risk later in life, according to researchers from Johns Hopkins University. Writing in the journal Pediatrics, the researchers claim that the blood test, haemoglobin A1c (HbA1c), should be used more frequently to screen youth for diabetes and related health risks, particularly as it is easy to administer in younger patients.

The HbA1c test measures the degree to which sugar molecules have linked irreversibly to molecules in red blood cells in the previous few months, making it an accurate marker of chronic hyperglycaemia (high blood sugar). There is also no requirement for overnight fasting before the test, thus making it less complicated and less prone to error than the fasting plasma glucose test.

The American Diabetes Association (ADA) currently recommends hyperglycaemia tests to screen for diabetes risk in youth who are at least 10 years old, are overweight or obese, and have at least one other risk factor such as a history of type 2 diabetes in close relatives, non-white race, or hypertension. With this in mind, the Johns Hopkins researchers analysed national survey and medical exam data on more than 14,000 youths ages 10 to 19, aiming to see how closely a positive result on different tests for hyperglycaemia is related to risk factors for diabetes and heart disease such as obesity and high blood cholesterol.

The analysis suggested that the current screening criteria, despite covering about a quarter of US children and adolescents, do not capture many youth with hyperglycaemia. For example, only about one-third of the youth who had hyperglycaemia as defined by a fasting glucose test would have been eligible for screening by the current ADA criteria.

“Current screening criteria miss a lot of children who are at high risk for diabetes,” said PhD student Amelia Wallace, lead author of the study.

The researchers also analysed the dataset to see how closely different measures of hyperglycaemia were linked to cardiometabolic risk factors. Here the HbA1c blood test was particularly useful as a screening tool, with stronger associations with the risk factors examined compared to the fasting glucose test. For example, having hyperglycaemia as defined by the HbA1c test was associated with a 4.1 times greater prevalence of obesity, whereas having hyperglycaemia defined by the fasting glucose test was associated with an only 1.8 times greater prevalence of obesity. Among youth analysed with HbA1c-defined hyperglycaemia, 51% were obese, compared to just 29% with hyperglycaemia defined by the fasting glucose test.

“Our study demonstrates that HbA1c is a useful non-fasting test for identifying high-risk youth who could benefit from lifestyle interventions to prevent diabetes and cardiovascular disease later in life,” Professor Elizabeth Selvin, senior author on the study.

“Some paediatricians have already been using HbA1c, but there hasn’t been sufficient guidance from paediatric organisations. I’m hoping that these results will help inform and guide the use of this important screening tool in clinical practice.”

Image credit: ©stock.adobe.com/au/David Pereiras

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