Future breath test for diabetes

Scientists may have discovered a new way of monitoring diabetes, by performing a breath test rather than the usual blood test, reported The Daily Telegraph. “Children with type 1 diabetes were found to exhale higher concentrations of methyl nitrites when they … have too much glucose in their blood”, the newspaper explained. It is hoped that this finding could lead to new methods of testing for and monitoring diabetes.

The story is based on a small experimental study. Although the initial findings suggest a potential role for breath analysis as an indicator of blood sugar levels, they only seem to be useful in certain situations. Without further research, these preliminary results cannot be extrapolated to conclude that this test will have a role in diabetes monitoring and management in all types of diabetes.

Where did the story come from?

The research was conducted by B.J. Novak and colleagues of Department of Chemistry and Clinical Research Center, University of California, USA. Funding for the study was from the National Institutes of Health and the Juvenile Diabetes Research Foundation and it was published in the peer-reviewed journal: Proceedings of the National Academy of Sciences.

What kind of scientific study was this?

This was an experimental study designed to see which chemical gases were contained in the exhaled breath of children with type 1 diabetes who were in an acute state of high blood sugar (hyperglycaemia – a serious medical situation which may occur if insulin injections have not been taken, or during illness).

In a previous study, the researchers found that they could detect raised blood sugar level in healthy non-diabetic individuals following a glucose meal (oral glucose tolerance test) by analysing the levels of chemicals in their breath. They predicted that in diabetic patients they might find other breath gases that could be used to detect hyperglycaemia.

A series of experiments was carried out on a group of 10 children with type 1 diabetes. In five of the experiments, the children were tested when they had a normal blood sugar level, and this was maintained throughout the two hours of the experiment. In the other 13 experiments, the children had raised blood sugar levels at the start of the experiment and this was gradually corrected with an infusion of insulin as the experiment went on.

In all the experiments, the blood sugar levels of the children were monitored by blood samples at 30-minute intervals; at the same time, the children breathed out into a container and the concentrations of particular gases in the exhaled air were examined. The researchers looked to see which gas was most closely related to blood glucose levels.

What were the results of the study?

Of the gases tested, the researchers found that the concentration of exhaled methyl nitrate most closely followed the levels of glucose in the blood; this close relationship was shown in 16 of the 18 experiments.

They found that in the experiments where the children’s blood sugar levels were kept at a constant level throughout, the level of methyl nitrate expired did not differ significantly from the start to the end of the experiment. However, methyl nitrate concentrations were significantly greater at the start of the experiments where the children had a raised blood sugar, and decreased significantly when the blood sugar levels had been corrected by insulin.

What interpretations did the researchers draw from these results?

The researchers conclude that the levels of methyl nitrate in the breath closely follow the levels of blood sugar. They say that their data “confirms the potential use of exhaled gas analysis as a non-invasive tool to monitor metabolic alterations, including hyperglycaemia in diabetic patients”. If this were possible, it would have “an immense global impact on diabetes screening, diagnosis, monitoring and prevention”.

What does the NHS Knowledge Service make of this study?

This study suggests that exhaled gas analysis may have a potential role as a part of diabetes management in the future, but that day is a long way off and much further research is needed. There are several limitations to this study, which the authors themselves acknowledge:

• This was a very small study on ten individuals; further studies involving on many more participants would be needed. 
• Methyl nitrate levels did not give a completely reliable reflection of blood sugar levels: there was a significant lag between the change in blood sugar levels and the corresponding response in methyl nitrate. This may limit the usefulness, as rapid detection is very important. 
• Studies in healthy participants showed a different concentration of exhaled gases from those in the patients with diabetes; this suggests that many more experiments would be needed before we could be certain of the relationship between blood sugar and exhaled gas in both diabetics and non-diabetics.
• On the basis of these findings, gas analysis could be suggested as a supplementary part to diabetes care only. Breath gas analysis has not yet been demonstrated to be useful for hypoglycaemia (very low blood sugar) – which is the more common, serious problem in young diabetics. 
• There is no current evidence that it could play a wider role in diabetes management. In particular, this study was carried out in children with type 1 diabetes; there is no indication that any future test would be useful for the growing numbers of people with type 2 diabetes, which is closely linked to high blood pressure, high cholesterol and obesity.