I have started the bsd and after two days my blood sugar has increased. Could there be any reason for this?

Are you eating enough fat to sustain your body ?
I had sugar problems and after taking advice on here I upped my fat levels and the sugar levels went down.
I think it has something to do with the liver releasing stored sugar.

This is a kind of second hand response – maybe someone can expand on this? I know my sister used to say her sugar went up overnight after eating what amounts to this diet. But it went down later in the day or something…? I know there was something about morning readings being affected by something else, and so being a bit of a red herring.

The theory behind it is that, during sleep, your sugar levels go down so your liver releases stored sugar to compensate for this. It’s a well known phenomonen called the dawn effect.
A snack containing fat a couple of hours before bedtime can help by giving your body the calories it needs during the night.

I’m with Bill on this one. It used to happen to me and was so disheartening. I could have a great reading before bed and wake up two or more points higher, not having eaten since 6pm. I was getting worried about needing to start on meds. so I googled it and found all the info.
Now I have a small glass of full fat milk or some cheese before bed. This is week three for me and I achieved my best fasting sugar yet, 4.4!!! If I’m tired and forget to have the fat/ protein combo before bed I can easily be high 5’s or 6+ the next morning.
I’m sure this would work for you too