Several posts have mentioned that in a serious, long-term disaster, diabetics unable to maintain a store of insulin will have a high death rate.
The following may help. Note that Jerusalem artichokes contain Inulin, not Insulin; however, the effects are similar for stabilizing blood sugar levels, according to several online sources (see Jerusalem artichoke, diabetes, and inulin). Inulin works for diabetes, pre-diabetes, and hypoglycemia; and helps with overweight which is related to a variety of medical conditions. It may also help to prevent the development of diabetes for those prone to it, or with mild cases.
Jerusalem artichokes are a natural source of inulin, and easy to grow. “Directly after harvest the carbohydrates are in the form of inulin, and are good for dieters and diabetics. The inulin changes gradually in storage to other starches and should then be regarded more like a potato by diabetics. Can be frozen or kept refrigerated in plastic bags. Can be stored un-dug in the garden, or in the root cellar as long as tubers are kept moist to prevent shriveling. The next crop can be planted from harvested tubers or you can leave some the in the ground to grow again.” (Johnny Seeds  2010 seed catalog, page 48).
Since Jerusalem artichokes take 90 days to mature, starting some plants indoors very early should provide a continuous supply for the year. The plants are perennial, and more than able to take care of themselves, but need to protected from animals digging up the tubers. Tubers look somewhat like ginger roots, have a sweet, nutty flavor, are about the size of large eggs, and can be eaten raw or cooked.
The Jerusalem artichoke is a native North American vegetable, is easy to grow to the point of being difficult to eliminate, and grows well in almost any garden soil, even in wet or dry soils. It grows from six to eight feet high, and makes a good windbreak or screen. Jerusalem artichokes are actually a species of sunflower, and have bright yellow, daisy-like flowers.
Their site should be carefully selected; make sure you want them there forever. The soil should be fertilized and aerated for maximum tuber size, since tubers will get somewhat smaller over the years. If you have lots of land, you may not care. The tubers also make excellent livestock feed.
Dosage varies, consult internet sources and check with a knowledgeable doctor, nutritionist or medically qualified herbalist. They have excellent probiotic qualities as well, which unfortunately means they can create a lot of gas. Best to start with small amounts and work up to the needed dosage. Internet sources suggest anything from two a month to one a day, depending on severity.
Oddly enough, for carbohydrate sensitive people, TEOTWAWKI  could result in obesity if protein supplies are limited, and people are living largely on wheat, beans and rice. Jerusalem artichokes should be particularly helpful for weight control for carbohydrate- triggered weight problems, but probably not for fat sensitive people. Recent research suggests that about half of the obese are genetically carb sensitive, and the other half fat sensitive, and weight control methods hat work for one group won’t work for the other.
On the other hand, if you are trying to prevent weight loss, it also helps to know which group you are in. To use Jerusalem artichoke for weight gain purposes, store it until the inulin changes to carbohydrate.
Best wishes from New York. – Janet W.