Just a little bit of info for a topic @daisymae has mentioned a few times.
Lactose is a form of sugar found in milk. It is a disaccharide. Disaccharides are sugars made of two units of different forms of sugar. Lactose is formed from one molecule of glucose plus one of galactose.
(Another example of a disaccharide is table sugar (sucrose) which is made of fructose and glucose).
When consumed, lactose is broken into glucose and galactose. Galactose is a simple sugar. It is one of three monosaccharides (the simplest form of a sugar) found naturally in foods (the other two being glucose and fructose).
An enzyme in the small intestine called lactase breaks lactose into glucose and galactose.
Generally, lactose will not cause as fast a spike as things like glucose, fructose, or sucrose. There are no catabolic pathways that metabolize galactose directly, so the body will convert galactose into a something it can use, a metabolite of glucose.
Galactose is converted into glucose 6-phosphate in four steps. This takes a little bit longer, but ultimately you get the BG rise from it, just like you can from any of the other simple sugars.
From Biochemistry, 5th edition:
If you are still reading this, maybe you are thinking, “Why does all of this matter?!?!?”
DaisyMae has mentioned a number of times how milk and yogurt products spike her.
So I am detailing all of this to give reference why those things spike her.
Anyway, there ya go, DM. The science behind your milk and yogurt spikes.