But what about diabetes? This is something about which I've given much thought, as a Type I diabetic. To survive without insulin is possible; to survive long may be less so.
Let's start with the sort of diabetes you're familiar with: Type II.
Type II Diabetes and the Apocalypse
When you eat so much junk food, exercise so little, and have such a slow metabolism that your body is constantly secreting insulin to cover the sugar in your bloodstream, you are also constantly storing body fat. And as that fat builds and your metabolism slows and your testosterone drops farther and farther, your body has to increase its insulin production even more.
It doesn't have to be this way--anyone can convert to a ketosis diet, drop the body fat, train your system to use fat--instead of glucose--as an energy source, and still be healthy. Don't let your nutritionist or other health expert fool you: your body can and will produce all the sugar your body HAS to have. Ever notice the recommended daily allowance for carbohydrates listed on labels? No? That's because it doesn't exist. Your liver is designed to respond to the hormone glucagon and make whatever's needed via gluconeogenesis.
You can drastically reduce the amount of meds you need or eliminate the need entirely with proper eating and keeping your body fat at a reasonable level for life on Planet Earth. Once you do, you'll use your own insulin properly, and you'll re-sensitize your cells to it. If you're running from zombies and 20+ pounds overweight, this will happen very quickly or you will be devoured. My recommendation: become a fat-burning machine now, and obviate the need for extra meds.
This equation is different. You won't respond better to your own insulin, because you don't make any. The zombies are here, and you're out of insulin. What now?
Insulin alerts your muscle cells to accept a glucose molecule or chain. Inside the cell, GLUT4 recognizes this secret knock, moves to the interior cell wall, and lets sugar in. Get this--exercise and muscle tone also cause the release of GLUT4. They won't release as much as when insulin knocks, but some is 100% better than none. I can't envision a circumstance wherein you're doing burpees 75% of the day to keep your blood sugar in check--that's really no way to live, so you're also going to have to make drastic food changes also.
1st Change: Major Hydration, Sir!
Water is your new best friend. It's now all that you drink, and you drink a lot. As the concentration of sugar in your bloodstream rises, your kidneys try to balance the level by peeing out as much as they can process. That means you're dehydrating, unless you're drinking more than enough to compensate. In case you didn't know it, your blood sugar reading is a measure of the concentration of sugar in the blood. Reduce that concentration with extra water, and think about what electrolytes will also need replacement.
Is a keto diet safe? Good question. Do you think the Vikings asked that question? Do you think Inuits asked that question? Do you think Tibetans worry that perhaps they should move to a warmer, flatter area, clear-cut some forest, and plant some wheat and strawberries? Here's a better question if you firmly believe your body needs whole grains before it can thrive:
Do you honestly think a human needs to plant several acres of grain, wait for it to ripen, harvest it, grind it, then mix it with other ingredients to produce bread or pasta before that person can be healthy?
Or does it make more sense to eat meat and vegetables, which you're designed to use as a fuel source? Here's a news flash: grinding up the heads of vast acres of grain, mixing it with all sorts of chemicals to extract the oils to produce "vegetable oil" is not what your body is waiting for, either.
Look at the picture above and describe what's unhealthy. You're designed to run on meat, chock full of saturated fats, veggies, and fruits if you can get your hands on them. Here's a study of how Type 2 diabetics respond to this sort of diet. Summary: they lost weight, their blood sugars improved, and they either quit needing meds or needed less (i.e., many of them magically quit having Type 2 diabetes just with a diet change).
Don't confuse ketosis with ketoacidosis. In ketosis, your body is trained to use fat primarily as an energy source, and you still CAN use glucose for energy, though it's going to get stored as body fat if you overeat. In ketoacidosis, you're unable to accept glucose into the cells, the quantity builds and builds, your blood turns acidic, and you start harvesting muscle for energy, and quickly die. This pretty much only happens if you're a Type I or a severe alcoholic.
If your body fat is above 13% or so, your fat-burning switch is set to "off." So change now! Once all the bread is gone from store shelves, you're going to eat meat and whatever you can grow anyway. There won't be any man-made carbs left.
Might as well develop a taste and metabolism for it now. If you do, you'll be healthier, fitter, and able to outrun not just zombie hoards, but also the average Type II diabetic who is running toward the grocery store to stock up on Ding-Dongs, rather than away from population centers, which is safer.
Do a Google or Bing search on the word "keto" followed by your favorite high-carb snack. You'll find that there isn't actually any compromise. "Keto pancakes." "Keto Chocolates." What you will discover is how emotionally tied to food you are. Your next 2 questions should be, "Why did I ever think I need man-made carbohydrates to be happy or healthy?" and "How can I find happiness in places other than food?"