I've been a type 2 diabetic for 11 years. Usually my blood sugar is under control; around 110 in the morning and 110-150 in the evening (6 PM). I had a root canal last week and the dentist gave me penicllin, which I've been taking since last Thursday. The tooth has been hurting all week, but the blood sugar has been fine. Today, all of a sudden, my 6 PM reading was 357! I ate lunch at about 2 PM, (a Reuben sandwich and a cup of chicken rice soup, not too much out of the ordinary for me foodwise or time wise.) Why did the blood sugar rise so much? The penicillin or the tooth problem? I'm going back to the dentist tomorrow for further treatment.