Readers following “The Personalized Diet” and regularly testing their blood sugar levels may find numbers that contradict expected readings. A question recently came into The Personalized Diet Facebook page about fasting numbers and Dr. Segal answered.

Dear Dr. Segal,
I’m a Type 2 diabetic, read your book and started testing myself following your protocol. Not surprisingly, white bread, sugar and fruit all cause spikes in my blood levels. I started adding other food items to my low-carb diet such as popcorn, low-carb bread and milk. The more recently added items don’t cause spikes, but my overnight fasting numbers have gone up 20 points since I’ve added them back into my diet. My normal fasting is between 90 and 95 and last week it was 115 to 125. Should I be concerned? – Frank

Dear Frank,
Thank you for your interest in our work and we’re happy to hear that you are following the program. In our experience, overnight fasting levels should not go up following this program and in fact should probably go down with time. Since fasting levels may fluctuate depending on when exactly you measure, we suggest that you monitor the levels on more days, and if a measurement is high, we would also suggest to repeat it 15-30 minutes after the initial test and after washing your hands (which may affect the measurement). We don’t expect that following the program and eating foods that spike your levels much less will cause an increase in fasting glucose levels.