Sober type 1 diabetics may sweat bullets at the breathalyser but Sydney-based endocrinologists say a false-positive alcohol reading during fasting ketosis is unlikely.

A study of 20 age, sex and BMI-matched type 1 diabetes patients and controls saw all participants blow below the lowest detectable blood alcohol concentration (<0.03) when tested with police breathalysers (Alcolizer LE5 and Lion Intoxilyser 8000), despite diabetes patients’ potential predisposition to elevated breath-acetone.

All participants had fasted overnight, 24 hours off alcohol and type 1 diabetes patients only had their basal insulin dose, forgoing short-acting insulin on the morning of testing.

Type 1 diabetes patients had a non-statistically significant fourfold higher mean blood 3-β-hydroxybutyrate concentration than controls, but no breath test produced a positive reading, the authors wrote in the Internal Medicine Journal.

“This may be due to the low levels of ketosis producing low breath-acetone concentrations,” they suggested.

The findings might help allay concerns that people with type 1 diabetes, who may be predisposed to elevated breath-acetone concentrations, could blow false-positives — a phenomenon seen with acetone consumption and vapour in the absence of ethanol, the authors wrote. However, the average HbA1c in diabetic participants was 7.3% (56 mmol/mol) meaning they had a lower risk of ketosis and ketoacidosis than patients with poor glycaemic control.

As such, “future studies should investigate the occurrence of false-positive approximate blood alcohol concentration readings in states of higher ketone concentrations (e.g. carbohydrate-restriction diets)”, and among SGLT2 inhibitor-users who are at higher-risk of ketoacidosis, the authors wrote.