A woman has beaten a drink-driving charge after she was diagnosed with a rare medical condition that causes her body to turn food into alcohol.

The motorist was found to be four times over the blood-alcohol limit when she was stopped last year in New York state.

Police pulled over the 35-year-old school teacher in a Corolla with a flat tyre after she was seen driving erratically, reports the Buffalo News.

The responding officer said the driver smelled of alcohol, was slurring her speech, and had glassy, bloodshot eyes.

The unnamed woman was able to recite the alphabet, but had trouble with other sobriety tests, police said.

She was charged with driving while impaired.

The woman did admit to having three alcoholic beverages earlier in the day, but her lawyers said she had not consumed enough to end up with the .33% reading.

A judge in the Buffalo suburb of Hamburg dismissed the charges earlier this month after medical tests showed the woman had "auto-brewery syndrome".

Her condition, also known as gut fermentation syndrome, involves an excess of yeast in the digestive system converting carbohydrates to alcohol.

Auto-brewery syndrome was first documented in the 1970s in Japan. Only a handful of cases have been reported around the world.

(Sky News)