welcome to hcm, i really appreciate your concern, random glucose level of 250-300 canbe a due to diabetes. However, it would be prudent to get a Hba1c done which would estimate the average glucose levels of the preceding 3 months. That would also clear our doubt if you have been having undetected diabetes for atleast 3 months. Normally, patients can have normal fasting levels with increased post meal glucose initially. Have you checked the random blood glucose before this? I would recommend you see a dietician and get a customised diet plan. Also start exercising if you are not active already - atleast 30 min walking daily. However, since you are having symptoms like nausea and light headedness you may not be able to exercise right away. You will need medications to control diabetes after getting a routine physical examination done. As of now, please drink plenty of water. You can also have lemonade with salt. That will make you feel a lot better. Regarding diet, cut down all refined sugar and products with white flour. Have small frequent meals and be mindful about the carbohydrate content of it. if your symptoms are getting severe go to ER otherwise its ok to show even after 2 weeks. please let me know if you have any further queries. thanks. regards