Hi
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First thing go and consult a good doctor, take their advice along with that you have to maintain Diabetic Diet and Daily 30 minutes brisk walk, 30 minutes exercise. If you are obese try reduce your weight.

Avoided: Glucose, sugar, honey, all sweets, chocolates, Ice creams and candies, red meat, tetra pack juices,
Restricted: Vegetables like Potatoes, yam, arbi, Sweet potatoes; fruits like mango, bananas, sapota, custard apple, avocado .Alcoholic beverages, carbonated beverages ,fried foods, Dry fruits and nuts, Salad dressings like mayonnaise, cream, etc, cakes and pastries, Tender coconut water, refined flours like Maida, skin out chicken. Use chicken breast which is contains less fat.

Foods to be used freely: Green leafy vegetables, tomatoes, cucumber. Radish, homemade soups. Without sugar, skimmed milk, Buttermilk, Whole wheat flour, Wheat flakes, Citrus fruits.

The only way to prevent / delay the onset of diabetes is to maintain a healthy lifestyle . Considering your age , you should keep yourself very active. Walking and moderate physical exercise will help . Cut down on carbohydrate rich foods like rice , increase intake of citrus fruits and protein rich foods . Check you blood sugar regularly atleast one every three months . Best Of luck !