What are sure signs of having diabetes?

Many. Test with FBS or aic or oral glucose tolerance. The following symptoms may be present thirst, polydipsia, polyphagia and frequent urinatiom and weight loss.
Thirst, hunger... Frequent urination, undue fatigue if concerned at all, see md to catch / treat early and can check sugars before person get these symtoms, to try to catch it early in people with family history of diabetes.
Thirst and urination. Signs of diabetes include getting really thirsty & urinating a lot. Because your body is trying to dilute your urine with water to get rid of excess sugar. Type 2 diabetes might also present with some signs like abdominal bloating, poor digestion, tingling in hands & feet, blurry vision. A lot of times unfortunately there's no signs in prediabetes and early stages of diabetes.