Your body requires certain nutrients whether you supply them (by eating) or not. One of the necessary nutrients is glucose. Several different metabolic pathways exist in your body to make sure that your brain and body systems have a supply of glucose at all times.
Your body can process carbs that you eat, or, if you fail to eat- it can convert protein (from muscles) and fat (from your fat reserve) into glucose to keep your body running. This process is called gluconeogenesis (it literally means to make new glucose). The liver assists in this conversion process. It has no way of knowing how much glucose you might need- so it churns it out until food arrives.
Meanwhile, your insulin feedback system reacts as if you were eating glucose from carbs (it can't tell the difference because all glucose molecules are the same regardless of the source), and your insulin resistant body is unable to clear the sugar - so your sugar rises even though you haven't eaten or haven't eaten enough.
Gluconeogenesis is just one of several starvation mechanisms- there are more and they're all designed to slow down your metabolism, maintain homeostasis, preserve your fertility, and keep you alive during times of famine- your body can't tell if you decide to underfeed it, or if food is unavailable- it behaves the same under both conditions. If you want to see what you are doing to your body- go read about how anorexia affects the human body- anorexia means underfeeding by the way- not just the horrible dysfunction known as anorexia nervosa- the process is the same every time you underfeed. You do damage.
If you want to regulate your blood sugars by diet and exercise- then you have to do the work to determine how little you need/how few carbs etc. You need to eat enough to NOT trigger the starvation mechanisms in your body. You can't read that in a book. What works for Jeannie, Lanie or me will most likely NOT work for you. If I eat like Lanie and Jeannie- my sugar is higher than if I eat higher carb. I need 75 - 100 carbs a day. I require fruit, vegetables, dairy, nuts, starchy vegetables ( carrots, winter squash, pumpkin, parsnips, rutabagas) and beans to keep my sugars in range and my A1c around 5.0-5.3. Lower carb, or if I eat certain grains, everything goes up for me- I know this because I've tested myself over and over, fine tuning my current requirements, and if you want to be med free- you have to do the work too.
If your pancreas is checking out on you- you will need medicine- it's not a failure, and it's not an option if you are doing damage to your body with extreme shifts in sugar levels. None of us wake up and say- I want to take diabetes medicine. If you want to stick around, you have to do what's best for your body- and it might include taking medicine.
I just want to live happily ever after-every now and then. Jimmy Buffett