Updated 30 August 2018

One blood test might be enough to diagnose diabetes

Currently, two blood tests are used to diagnose diabetes, which may be expensive or burdensome for some patients.

New research published in the journal Annals of Internal Medicine, suggests that a single blood test could confirm type 2 diabetes, saving patients time and health care costs.

Currently, it's recommended that a blood test focused on elevated fasting levels of blood sugar (glucose) or a blood component called glycated haemoglobin (HbA1c) be confirmed with a second blood test at a follow-up visit.

But taking the test twice takes up time and money and could still result in missed diagnoses, said a team from the Johns Hopkins Bloomberg School of Public Health in Baltimore.

A major simplification

In the new study, researchers led by Hopkins epidemiologist Elizabeth Selvin looked at data on more than 13 000 people in a long-running US heart disease study. The study began in the 1980s, and along the way has recorded valuable data from participants, including diabetes test data.

Selvin's group analysed that data, and reported that a positive result for glucose and HbA1c from just a single blood sample can confirm type 2 diabetes.

This could change care, "potentially allowing a major simplification of current clinical practice guidelines," Selvin said in a university news release. "Doctors are already doing these [glucose and HbA1c] tests together, if a patient is obese, for example, and has other risk factors for diabetes, the physician is likely to order tests for both glucose and HbA1c from a single blood sample.

"It's just that the guidelines don't clearly let you use the tests from that one blood sample to make the initial diabetes diagnosis," she explained.

Diabetes is treatable, but about three million Americans with the disease don't know they have it.

"I'm hoping that these results will lead to a change in the clinical guidelines when they are revised in early 2019, which could make identifying diabetes a lot more efficient in many cases," Selvin said.

Better treatment and outcomes

"Diabetes moves fast, and the cost of diabetes has increased more than 20% since 2012," noted Dr Robert Courgi. The new study "helps us move quicker to treat diabetes," he said.

"By diagnosing diabetes quicker, we can improve outcomes," said Courgi, an endocrinologist at Northwell Health's Southside Hospital in Bay Shore, New York. "The current standard is to delay diagnosis with repeat office visits and blood work. Now we can educate the patient sooner and start treatment earlier to prevent complications of diabetes such as heart attack, dialysis and amputations."

Dr Gerald Bernstein coordinates the Friedman Diabetes Program at Lenox Hill Hospital in New York City. He agreed that quicker diagnosis could mean better treatment and outcomes for patients.

"The CDC reports that greater than 52% of the US population has either clinical diabetes or prediabetes," Dr Bernstein noted. "Given these numbers, any abnormality of glucose should be regarded as sufficient reason to start preventative treatment with an education programme, lifestyle change and first-line medication such as metformin."

According to Dr Bernstein, if only one diagnostic test were needed, "this would mean that a follow-up visit would be a look at the treatment benefits, rather than a confirmation of an abnormal glucose".

Image credit: iStock


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Dr. May currently works as a fulltime endocrinologist and has been in private practice since 2004. He has a variety of interests, predominantly obesity and diabetes, but also sees patients with osteoporosis, thyroid disorders, men's health disorders, pituitary and adrenal disorders, polycystic ovaries, and disorders of growth. He is a leading member of several obesity and diabetes societies and runs a trial centre for new drugs.

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