Hello Thanks for usingHCM for your health problems. I read carefuly your question and understood your concern. You doesn t explained clearly why your dad was prescribed the antibiotic and antimicrobial therapy anyway i presume that it has an infection when he was discharged. The infectious disease and maybe the psychologic stress that is caused by the infection can raise the blood glucose in a diabetic person. His blood glucose is high and nausea can be a symptom of diabetic ketoacidosis. Diabetic ketoacidosis is a serious complication of diabetes that occurs when your body produces high levels of blood acids called ketones. For this reason my advice is to check his ketone level in the blood and in the urine.If the result is positive you need to take hime in an Emergency Room as soon as possible because it can be dangerous if it is not treated. In most cases, people with diabetic ketoacidosis need to be treated in hospital. If the test of ketones in his blood and urine is negative,i suggest to consult an endocrinologist in your area because in my opinion the metformine monotherapy is not effective and it is necessary to add another antidiabetic drug. I want to remember that the diabetic diet and more physical activities(if not contraindicated)are other important elements for the control of your dad s diabetes.I recommend to not be negligent. Hope i have answered to your question.If you have further queries,feel free and ask. For treatment recommendations, and individual therapy,you can ask me at HealthCareMagic at my private link: bit.do/hcm-Dr-Xhardo. I will be happy to help. Take care.