What are some tips on preventing diabeties?

Start with a balanced diet. Assuming you are otherwise healthy I would recommend a diet high in protein, with moderate carbs, and low in fat. The carbs that you do eat should not be from refined, processed foods and simple sugars. Try and eat more complex carbs like sweet potatoes, yams, oatmeal, and whole wheat products. They will break down slower keeping your insulin from spiking. Any simple sugars that you do eat should come from fruit, as opposed to candy and sweets. Also make sure you get plenty of vegetables throughout the day, especially ones with soluble fiber as soluble fiber helps regulate blood glucose.
Aside from proper diet, make sure to exercise regularly, for at least 150 minutes per week. If possible try to get at least 20-30 minutes of strength training in per session. Strength training specifically has been shown to increase insulin sensitivity. It will also help build muscle tissue which is also a major help.
Finally, visit your doc for check-ups so they can check your lab values regularly to make sure that what you're doing is working. Hope that helps!

Start with a balanced diet and nutrition. Seeing your doctor monthly check up.

In just a few weeks, 96% of these doctors patients are able to stop ALL diabetes medication and insulin injections. http://commondiabetes.com

Don't smoke and stick to healthy eating and exercise and don't gain weight.

if you have diabetes avoid drinking drinks that have a high amount of sugar in it, like cola-cola will not be suitable for a diabetes patient

Healthy eatting, exercise, seeing your doctor.