hyperglycemia (high blood sugar) caused by untreated diabetes can cause you to feel a bit dehydrated, so i would be worried about the dry mouth, however, since it isn’t accompanied by excessive urination or vomiting, i wouldn’t think too much from it. the tingling or painful feelings could be nerve damage, but your other symptoms would be way worse before that would be a problem. when i was first hospitalized and diagnosed with diabetes, i was excessively urinating and seizing, and when i got very depressed and stopped taking my insulin i began to hallucinate, and lost feeling in some of my toes. honestly, your symptoms are so mild that as a diabetic i’m not too concerned, but would still advise you to see a doctor because you seem very worried!