Increased fasting blood glucose in low-carb diets

When you're relatively insulin resistant, even a slight rise in glucose production or intake can cause a blood glucose (BG) peak.

It goes something like this: low-carb intake reduces insulin; low insulin activates hormone-sensitive lipase (LIPE); LIPE breaks down triglycerides in the muscle or adipose tissue and releases non-essential fatty acids (NEFA); NEFA induces insulin resistance.

[[MORE]]In the morning, you normally have a growth hormone surge; that causes NEFAs to peak, and you have a spike in fasting BG (FBG).  When you eat a low-carb meal, the protein in it will cause insulin to be released -- although not nearly as much as if you ate carbs.  The insulin inhibits LIPE, so NEFAs decline; insulin sensitivity comes back; BG goes down.

However, if you have too much protein, BG can decline too far; then the body secretes catecholamines (adrenaline) to help bring BG back up again; that stimulates GNG (I'm not sure of the mechanism--it may be by stimulating glucagon release from the pancreas); you start to feel jittery; if it happens in the evening, it can contribute to insomnia.  Sometimes people mistake the jitteriness from low BG with what they feel from caffeine.  Also, you can become acclimated to the elevated catecholamine levels, which is why diabetics can be at severe risk for not recognizing low BG (a diabetic relative of mine passed out at the wheel and was killed as a result of this).