blood sugar level question

Hi,
I am on day 6 of what I hope will be a 30 day fast (I will see how I feel) .I have done a 14 day fast before with little trouble.

I am completely healthy (except that I am a bit overweight) but have many family members with diabetes so I have a blood Sugar machine to keep me honest...
When I fast my blood Sugar level drops to 40-45.
I feel good a bit tired sometimes but generally feel really fine.

Is this a problem?

Thank you!