When the blood glucose level gets too high, it can cause many symptoms. However, if the rise in blood glucose came on very slowly, you may not even have noticed the symptoms, or you may have thought they were due to something else. All of the symptoms can be caused by other things, but when several of these symptoms occur together, you should certainly think that you might have diabetes and should get yourself tested. When your blood glucose level gets high, your kidneys try to get rid of the glucose, and so going to the bathroom for excessive amounts of urination is the commonest symptom of diabetes. Since this gets rid of lots of extra water out of your body, you end up getting dehydrated and feeling very thirsty as a result. Funnily enough, many people are not surprised that they are going to the bathroom a lot. They assume that it is because they are drinking so much extra fluid that they need to go to the bathroom so much (rather than the other way around).
Diabetes can also affect your vision. Even though you will not notice any change in the size of your eyes, the inside of your eyeball swells with extra fluid. The hard lens inside the eyeball also begins to swell with extra fluid, but it takes much longer for the lens to swell or to shrink when the glucose levels change; and so sometimes the lens is too big, and sometimes it is too small for the size of your eyeball. This causes blurred vision. Sometimes people are so troubled by this that they go to their eye doctor and end up getting new prescriptions for glasses or contact lenses to compensate. If you do this before you realize you have diabetes and then get treatment to bring your blood glucose levels back to normal, then you will be annoyed that you spent all that money on new eyewear. Your new glasses or contact lenses will no longer work for you once your blood glucose levels are back close to normal and your eyeballs and lenses have returned to their normal size.
Some people also feel incredibly tired when they are developing diabetes. They may feel very hungry and may be losing weight no matter how much they eat. This is especially likely with type 1 diabetes, where your body makes so little insulin that you can't prevent fat and protein being broken down in your body. If the diabetes goes undiagnosed for even longer, you may feel drowsy and nauseated. Some people end up being taken to the hospital because they are so weak, or may even have passed out into a coma. When diabetes comes on more slowly, you may not notice any symptoms at all. Sometimes it is diagnosed when you go to see your doctor for another problem, such as erectile dysfunction or numbness in the feet. The high blood glucose can also make you at higher risk for getting certain types of infection such as yeast infections in your groin, penis, or vagina.