Answer #1: Stay active, exercise regularly, eat sensible meals, eat nothing to excess, get plenty of sleep, stay as stress-free as possible, and don’t eat anything that hasn’t been thoroughly cooked or washed, especially when traveling.
Answer #2: Consider eating a low-carbohydrate/low glycemic diet as a permanent lifestyle change. The key to avoiding diabetes is weight control and also avoiding consumption of high levels of glucose/fructose in the form of table sugar, high fructose corn syrup, and other simple carbohydrates that lead to an increased inflammation and insulin response within the body.
Make vegetables the basis of your diet. Eat moderate amounts of protein. Strictly limit or eliminate grains and starchy carbohydrates (like bread and rice). Do NOT eat a lot of fruit. Fruit = fructose. Eat fruit sensibly.
Daily exercise will lower insulin levels as well.