TORONTO - Ontario's highest court has dismissed an appeal from a man who argued his guilty pleas to three drug charges should be overturned because of his diabetes.

Brian Burrett pleaded guilty in 2008 to three drug trafficking offences for selling cocaine to an undercover police agent on three separate occasions.

Burrett, who has Type 1 diabetes, takes five injections of insulin per day otherwise he experiences dizziness, difficulty concentrating and speaking, weakness, confusion, anxiety and vision changes.

He appealed his convictions, arguing that on the day he entered his pleas he was experiencing some of those symptoms and felt like he was in a "drunken state."

Judges at the Court of Appeal for Ontario found no evidence on the record to support what they called Burrett's "bald assertion" that he didn't understand what was happening in court when he pleaded guilty.

The court upheld his convictions, saying a review of the transcript suggests Burrett fully and voluntarily participated in the proceedings, including making a statement of regret.