Just thirst in general or thirsty specifically for sugary stuff? Both are a sign to get yourself in to the doc so they can check out your glucose levels and how your body is processing sugar. Simple test really, assuming they do the most likely one. They'll give you a big bottle of something that tastes like really sweet gatoraid or orange soda, not let you eat anything or leave the lab, and check your glucose at the start of the test and then every hour for five hours or until they have to stop the test. Time consuming, but not to bad. Bring a big book that you wont get board reading.
If you have diabetes or pre diabetes that isn't being treated, you either have insufficient insulin production (type 1) to process the glucose in your blood or you have plenty of insulin but your cells have lost sensitivity to it (type 2). The main results are similar, you can't process the glucose into your cells so it results in high blood sugar. Primarily in type 1, but also possible in type 2, at high enough levels you also can develop diabetic ketoacidosis which can be more immediately bad juju. In this possibility, drinking sugary stuff is a BAD IDEA. Either way, proper diet and medication means it's becoming an increasingly manageable disease if the patient does their part and doesn't ignore it.
If you are getting jittery, tired, sudden extreme hunger or craving for sugar, etc. that can be a sign of hypoglycemia/reactive hypoglycemia. In short terms, kind of the exact opposite of diabetes. In this possibility, you're either producing to much insulin or your cells have developed a hyper sensitivity to insulin meaning you burn through glucose very fast. Typically, someone with this condition can expect to start experiencing low blood glucose levels 2-3 hours after eating. Once it's caught treatment is fairly simple- eat every couple of hours with a good balance of carbs and protein, no meds needed and minimal finger poking. I was diagnosed with this a couple of months ago and it's not so bad once the doc give you the run down and you know how to deal with it. A might inconvenient, but manageable. Though that test I mentioned? It'll be a big less fun. Because it WILL induce a glucose crash. A rather more dramatic then normal one, that comes on out of no where as you've been fed straight glucose with no protein to help moderate it. On the bright side a bunch of cute nurses will suddenly flock around you with glucose tablets, offering all sorts of yummy fresh baked goods, and one particularly cute one will even offer to swipe you a sammich from the cafeteria. They will then keep you company and engage you in polite conversation while you enjoy this new found bounty. Or they could just be making sure you don't pass out try to sue them while checking your levels every five minutes waiting for you to hit 70 so they can kick you out for being a jackass and not telling them that you were starting to feel funny, but I digress.
Or, another likely cause. It's the middle of summer and you're just thirsty. In this case you'll just be mildly annoyed you were denied your morning coffee, have had nothing to eat all morning, and you're arm has a bunch of extra holes for no good reason. Better safe then sorry.
