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Many people get a surprise when the doctor hands them a diabetes or a prediabetes diagnosis. They go to the doctor for a routine checkup or because of some specific complaint, such as back pain or fatigue, and their lab work comes back with the bad news that their blood sugar is way too high.

More: 15 Common Risk Factors of Type 2 Diabetes

If they were really paying attention to their bodies, however, they wouldn't be surprised. As diabetes develops, it announces itself in all kinds of ways, some of them subtle and others really in your face.

Feeling thirsty

Your mouth feels dry, and you want to keep your lips planted on the water fountain, despite the line of people forming behind you.

Dehydration is actually about your brain, not your mouth, even though your mouth is dry. Don't believe me? Your brain cells need a steady supply of glucose. When your brain is bathed in overly concentrated sugar water, it will summon fluid from any source to dilute the uncomfortable fluid surrounding each cell. Your brain gets this fluid from other cells, which leads to dehydration. You may have the urge to drink copious amounts of fluid as your body tries to overcome the lack of water.

Soda pop junkies, you're fooling yourself if you think that drinking soda will hydrate you. It never will. For now, drink more pure, filtered water. You can do it!

Frequent trips to the bathroom

It makes sense that if you are drinking more water because of constant thirst, then you will be urinating a lot too. You are staring at (or sitting on) the potty more than normal because there is too much sugar in your blood and your kidneys are getting a serious sugar bath.

If your kidneys could speak, they'd say, "Hey, what's the deal here? I'm overwhelmed, so I'm going to pull extra water out of your blood to dilute all this sugar!" Essentially, the floodgates open as your kidneys continuously draw extra water out of your blood in an effort to dilute the sugar bath coming through. All this water fills your bladder, and this sensation causes the urge to pee. Then you become thirsty again, and have to drink more water in an attempt to rehydrate. And the cycle continues.

More: 13 Tasty Diabetes-Friendly Snacks

Your kidneys do their best to eliminate excess glucose. The amount of protein spilling into the urine also increases with time, which interferes with normal kidney filtration. If your kidneys can't filter wastes properly, toxins build up in your bloodstream. The insidious thing is that kidney damage can occur even when blood sugar is controlled by medication.

Weakness and fatigue

Many people feel run down and don't realize that their chronic exhaustion is related to blood sugar problems. The symptoms of fatigue can be easily masked with a mocha latte. Starbucks has a booming business, in part because of the ever-expanding population of tired, weak people with insulin resistance (and no wallet resistance).

When the glucose from your meals can't get into your cells, your cells can't make energy, so you feel tired all the time. Not to mention that exasperating sense of hunger when you just ate a little while ago. What's up with that? If glucose from your meals is locked out of your cells, you never get the energy boost or that satisfying sense of fullness after you eat. Bummer.

Numbness and tingling in your hands or feet

This sneaky symptom is really about nerve damage, and can take months or even years to show up. Your doctor terms this pain neuropathy. Neuropathy occurs because the bloodstream is overwhelmed with glucose, which is like acid to your nerves. It damages the delicate nerve endings that extend to the hands, legs, and feet. That's when you start to feel the pain, numbness, tingling, itching, and other weird sensations that you may be experiencing. If you have this symptom, you should discuss it with a neurologist in addition to your regular doctor. The good news is that for many people, it can be minimized or managed with several inexpensive, over-the-counter supplements.

Blurry vision

If your blood glucose levels remain high, fluid may be pulled from your tissues for dilution purposes—including fluid from the lenses of your eyes. This may affect your ability to focus. Also, teeny tiny capillaries that lead to your eyes become damaged from all the free radicals. Free radicals are damaging molecules that people with diabetes produce in alarming quantities. This is why antioxidants are so important for anyone who has this disease. Antioxidants help neutralize free radicals.

Skin problems

Some people with type 2 diabetes have patches of dark skin in the folds and creases of their bodies—usually in the armpit, neck, knuckles, and groin. It almost looks like dirt, except you can't wash it off. Sometimes it looks velvety or bumpy. There may be skin tags around these darkened hyper-pigmented areas. This condition, called acanthosis nigricans, is a sign of insulin resistance. It means that your body is producing too much insulin in response to excessive blood glucose.

Infections

Frequent bladder and vaginal infections can be a particular problem for women with diabetes. You would think that taking antibiotics would simply cure a person's infection, but it's not that easy. In the general population, not just among people with diabetes, antibiotic resistance has weakened our ability to defend ourselves against microbes. This resistance is a deadly consequence of many years of indiscriminate prescribing of antibiotics.

Wounds and skin infections are slow to heal in the person with type 2 diabetes, and skin infections that cannot be healed could lead to gangrene and ultimately amputation of a foot or limb. It's much easier to prevent a wound than it is to cure it, just as it's much easier to not smoke than it is to cure lung cancer.

Losing weight without trying

Many people with diabetes or prediabetes want to munch all day. Because their cells ignore insulin, which can no longer effectively move blood sugar (energy) into those cells, their muscles and organs feel famished. Improper fluctuations of hormones such as ghrelin (a hunger hormone) and leptin (a feel-full hormone) complicate things and trigger intense hunger. The interesting thing is that you may lose weight without even trying, even though you nosh all day long. Great, right? Wrong!

This kind of weight loss causes you to lose muscle mass. It occurs in part because your body is looking for some energy or fuel (think glucose), and it breaks down muscle cells to get it. Without a constant source of glucose in your cells, your muscle tissues shrink. This is especially noticeable with type 1 diabetes. With type 2, this symptom of weight loss is imperceptible for years because most people with type 2 diabetes are overweight to begin with and the subtle weight loss flies under the radar. Losing weight is important if you have diabetes, but you want to lose fat, not muscle.

This article originally appeared on RodaleWellness.com.