Scientists have found that taking extra vitamin D3 is one of the most potent preventative measures for prediabetes or type 2 diabetes. We know this because low vitamin D3 is characterized by an increased risk of prediabetes and type 2 blindness. In a study in Taiwan, the researchers found that people who did not exercise were overweight or had too much body fat are significantly more likely to develop type 2 diabetes if they don’t correct their vitamin D deficiency first.  Researchers in Sweden followed 900 people over 20 years with low vitamin D levels but no other known risk factors for diabetes. They found that those who didn’t supplement developed the disease anyway. It was concluded that regular supplementation with vitamin D reduced the risk of diabetes. A recent study in Finland followed 2,675 middle-aged men without known heart disease but with slightly high blood glucose scores who were at an increased risk of developing type 2 diabetes over 10 years. After taking into account factors such as weight gain and family history of diabetes, it was found that those who used vitamin D supplements at least once a week reduced their risk of developing type 2 diabetes by 45 percent compared with men who didn’t. In general, those who take 1,000 to 5,000 IU a day of Vitamin D can prevent or delay the onset of type 2 diabetes.