You can take antibiotics not having significant interaction with anti-diabetics by consulting a physician. But wait, 95% of upper respiratory tract infections are viral and does not require antibiotics routinely. But being a diabetic in insulin, u m8 require. Leave the decision to your Physician

yes you can . - Avoid cold food and water, preferably have hot food and water - Don't skip meals have a liquid diet containing soups and progressively increase to solid diet as per how you can tolerate. - Have food rich in vitamin C such as oranges to help build immunity. - Drink plenty of fluids, drink 3 liters of water per day - Do salt water gargling with lukewarm water thrice a day - Do steam inhalation (plain steam) thrice a day and apply vaporub over your chest and nose - Maintain good personal hygiene(Wash you hands regularly) - Rest plenty, body heals while at rest If the condition persists or worsens visit nearest ER at earliest