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Jeffery could very well have diabetes, but Jeffrey is in the age group where hyperthyroidism, kidney disease, and urinary tract infections are also quite possible. The way to differentiate between these and get a diagnosis is for Jeffrey to have a blood profile test and a urinalysis.
Then with a solid diagnosis, treatment would be specific for his needs. Polyuria and polydipsia (urinating a lot and drinking a lot) are signs of disease, and now when he is feeling so well is the best time uncover a likely problem and to initiate treatment.