IF is actually really good for a type 2 diabetic.
Dr Fung has a really good explanation in his book The Diabetes Code. I'll try not to fuck it up too badly.
Type 2s pancreas still produces insulin in response to eating. The problem is the insulin resistance. Insulin is the key to transport glucose into cells. Insulin resistance happens when the cells are overfilled with glucose. The key gets harder to turn, so the pancreas responds by releasing more insulin and basically turning the key harder and stuffing more glucose into the already full cell. We can't measure how much glucose is in your stomach cells, for instance, only the blood. Doctors typically don't measure insulin levels or insulin resistance, if the patient is not controlling the diabetes they give them more insulin, which lowers the blood sugar but the overstuffed cells become damaged and cause complications. That's aside from the damage the glucose itself does to the blood vessels.
In a metaboliclly healthy person three meals a day gives the cells enough time to use the glucose. In a type 2 diabetic each meal just stuffs the cells further, making them sicker. We all know these fatties eat more meals than a hobbit, and every meal means more insulin used. It is possible to wear out your pancreas to the point where it just stops making anything at all, at which point you do need insulin like a type 1 but you have the insulin resistance of a type 2.
Fasting means the pancreas has more time to rest between sending out insulin and the cells have more time to use the glucose in them.
Dr Fung recommends the 16:8 fasting for his patients, eat low carb in an 8 hour window, fast for 16 hours. If they come in with super high sugars, like Chantal, he recommends eating one low carb meal of only 400 calories and fasting the rest of the day. Up to three days in a row. I would not recommend that to anyone not under medical supervision though. its unlikely a three day fast would harm anyone, but it's better safe than sorry.
He says the longer you follow this routine the more the insulin resistance will fall and the more the body goes back to acting like it should. Weight loss typically follows, but is not going to make a fatty skinny. On average of his patients most lose about 50 pounds. However, the insulin resistance/producing too much insulin never really goes away, which is why this is not considered a true cure.
The danger with fasting is, of course, hypoglycemia. However, a blood sugar of 300 is going to take literally days to come down without insulin to force it. Even with Metformin it'll take at least 24-48 hours of no carbs to return to normal. It is very definitely a concern to be aware of, but hypoglycemia has a very distinctive feel. A little education on the symptoms is enough to make it not dangerous to most non-retards. All you need to do is eat 15 carbs (three pieces of hard candy, a slice of bread, etc), wait 15 minutes, if still too low repeat. And trust me, the desire to stuff your face is one of the symptoms. Hypoglycemia starts giving symptoms at 70 (for us fag's) and only gets dangerous at 55. I've never ever had it get below 65-70 before I'm stuffing my face with every carb in the house. I've been doing IF and low carb most days for a year, I've not had hypoglycemia once. Most diabetics I know who do this type of thing as well report the same, after decreasing their meds appropriately. This is the biggest reason why diabetics need to work with their doctor when doing this.
In general though, a type 2 is perfectly capable of fasting 16 hours. After all, as much as we mock Amber for it, sleeping IS fasting. You don't eat or drink anything while asleep, so there's eight hours. Wait until lunch to eat, there's your 16 hours. After a few weeks your body stops feeling hungry outside of your chosen hours.
