1. Sugar does not cause Diabetes. In fact, many academic conversations about sugar glucose, sucrose, fructose, lactose) are about whether or not it protects against Diabetes and by how much, as you can see in this review. Considering sugar's ability to decrease some of the hallmarks of Diabetes, such as elevated lactate and others it would be no surprise if it, in the end, was found to actually be medicinal in some sense. Or at least in certain contexts.
2. Grains do not cause Diabetes. Again, the question is not whether or not they are causative of Diabetes, but how protective are they, what types are protective, and for whom are they protective.
3. Dieting does not improve Diabetes. There was a big headline story a while back showing that extreme calorie restriction can reduce or even eliminate Diabetes. Sure, reducing food intake can temporarily improve the biomarkers for many health conditions. It is not a lasting cure, and repeated dieting is associated with higher rates of obesity and type 2 Diabetes, perhaps even causing the conditions it is purported to cure as I have asserted for many years both on this blog and in my books.
4. Lowering your blood sugar doesn't necessarily improve your health. Uh oh Scooby. In fact, one study showed good glucose control led to worse health outcomes. This one too. In my experience, when diabetics and prediabetics reduce food intake or carbs to lower blood glucose levels, health problems ensue equal or greater to the problems caused by high blood sugar. Starving oneself of glucose is not a solution to a very complex and multi-faceted disease. When it comes to improving any health problem, you cannot chase a number or numbers with disregard for all the other markers of proper function (hair, skin, sleep, sex drive, digestion, etc.).
5. Diabetes is not a disease of glucose excess. Well sure, it is if all you are focused on is the blood. But glycogen storage and intracellular sugar are reduced in Diabetics when compared to normal people. Diabetes should probably be thought of as a disease in which sugar can't get to where it's supposed to go (cells and muscles), and blood levels rise to compensate, which is perhaps why lowering blood glucose levels can cause even more harm. More discussion on this can be found in 12 Paleo Myths.
6. Carbohydrate consumption does not damage beta cells in the pancreas that are vital to insulin secretion. There's not much evidence that glucose, singlehandedly, plays a role in damaging beta cells. There is a great deal of evidence that free fatty acids, uncoupling protein-2, free radical oxidation, inflammation, and many other factors are involved in beta cell dysfunction.
This is just scratching the surface. There's no need to be exhaustive here. All this should do is demonstrate the far greater complexity that lies beneath the superficial beliefs and opinions of those less informed.