One slip shouldn't change the A1c much at all since it is really a measure of your average blood sugar over 90 days. Is it accurate? I think I remember reading that low carbers have longer living red blood cells so as they age they accumulate more glycation.

My friend is a Type II and he had an A1c of 9 and he finally started keto and his A1c is down to 5. I tried years and years ago to get him to try it!