It was getting late and I was short on ideas that interested me. Fortunately, I just so happened to pick up a trivia book my brother left around. The book is called Your Pinkie is More Powerful than Your Thumb: And 388 Other Surprising Facts That Will Make You Wealthier, Healthier, and Smarter Than Everyone Else and the author is Mark Di Vincenzo. The "facts" in the book seem to be hypotheses based on a studies. But one (on page 23) gave me an idea.
The book says: In the diabetes study, researchers followed 10,892 middle aged smokers who did not have diabetes from 1987 to 1989. Those who quit increased increased by 70 percent their risk of developing diabetes for the first six years after they quit [compared to people who'd never smoked]. Those who continued to smoke also increase their risk for developing diabetes- but by only 30 percent.
I looked for this study. I don't see it, but I did find another study (a Japanese one), of thirty thousand people, roughly 900 of whom reported quiting smoking between the first measurement and the second, who did not report resumed smoking. It followed all of these people for a few years. The fasting blood sugar of those who quit was significantly higher the next year, and the year after that, but then it began to go down. http://www.jstage.jst.go.jp/article/jea/21/6/21_431/_article
So: smoking increases diabetes risk and quitting smoking will, at least temporarily, make the risk a little worse.
If you already have diabetes, there are plenty of reasons to quit smoking, even if you are convinced you will die too young to worry about lung cancer.
Smoking messes with circulation; so does diabetes. Diabetic smokers have higher risks for a variety of complications compared to nonsmoking diabetics.
For instance, in the Wisconsin Epidemiology Study, which has been following 943 people diagnosed in a particular part of Wisconsin with type 1 diabetes under the age of 30, for about thirty years, the risk of having a toe, foot, or leg amputated after 25 years with diabetes was roughly 10%. Not exactly a small risk, IMHO, but the majority of participants had A1cs above 9%. The biggest risk factor for an amputation (in this group) was being a guy (triple the risk compared to women). The next biggest risk factor was smoking. People who had quit smoking had an intermediate risk. A1c was a significant risk; the people writing this up did not rank it as a higher risk factor than smoking and sex because they were looking at how much a difference in A1c mattered if you had an A1c of 8% vs 11%, which didn't matter as much as the difference between 11% and 15%. Running a crazy high A1c like 15% will run you into all kinds of trouble.The Article
BTW, not so fun fact (cited in article above) if you compare type 1 and type 2 diabetes with the same diabetes duration, the type 2 diabetics are at higher risk of having something amputated.
In the same population, smokers were two and a half times more likely than non smokers to have had severe hypoglycemic episodes in the previous year- either because smokers don't take care of themselves generally, or because smoking makes your hypoglycemia awareness worse. Severe hypoglycemia was hypoglycemia that made them pass out or have an overnight hospital stay (or both).