9 Signs Your Blood Sugar Is Too High

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On July 1, 2025

Spikes in blood sugar levels can feel different for everyone. “Not everyone will have the same symptoms, and some individuals will have no symptoms at all,” says Lori Zanini, RD, CDE, a Los Angeles-based dietitian and author of The Diabetes Cookbook and Meal Plan for the Newly Diagnosed.

If you think your levels may be out of control, it’s important to take action, even if you’re feeling totally fine. “Symptoms of uncontrolled diabetes may not appear until prolonged hyperglycemia (high blood sugar) has been present,” says Mary Ann Emanuele, MD, an endocrinologist, professor, and medical director of inpatient diabetes at Loyola University Medical Center in Maywood, Illinois. Having diabetes that is not well managed can increase your risk of related health complications, such as stroke, heart disease, and nerve damage.

Adjusting your medication, with the help of your healthcare team, can make a difference.

1. You Urinate More Than Usual and Are Very Thirsty

Urinating very often is a common but not-so-obvious sign of blood sugar that is too high. “Excessive urination, known as polyuria, occurs when glucose builds up in your blood and your kidneys begin working harder to get rid of the extra glucose,” says Zanini. If your body can’t keep up and adjust blood sugar so that it returns to a normal level, the excess sugar is flushed out of your body through urine, she says. You may become dehydrated and feel very thirsty as a result.

2. You’re Hungrier Than Usual but Losing Weight

Being hungrier than usual can signal a common symptom of diabetes: polyphagia, or extreme hunger.

And although you’re eating more, you may be losing weight for no apparent reason if your blood sugar levels are too high.

“Since your body is not getting energy from the preferred source, glucose, it has to turn to muscle and fat,” Zanini says. “When your body starts breaking down muscle and fat for energy, you experience unintentional and unhealthy weight loss.”

In addition to these changes in weight and appetite, you may notice weakness in your muscles and experience more frequent falls, Dr. Emanuele says.

3. You Constantly Feel Tired and Fatigued

Fatigue and feeling very tired are symptoms of unmanaged blood sugar levels. “Simply put, when your body doesn’t have sufficient amounts of insulin, the sugar is staying in our blood rather than getting into our cells to be used for energy,” Zanini says. Frequent urination can lead to dehydration, which is another contributing factor to fatigue.

4. You Have Noticeably Blurry Vision and Frequent Headaches

High blood sugar levels can change the shape of your eye lens, making it hard to focus properly and causing blurry vision. As a result of these vision changes, you may have a hard time working and driving. You may also experience frequent headaches, Emanuele says.

Your vision may go back to normal once your blood sugar is well managed. If you experience any eye-related symptoms, it’s important to speak with your healthcare team for treatment.

5. You Develop Sores That Heal Slower Than Usual

Diabetes causes nerve damage and affects circulation, especially in the lower legs and feet. Nerve damage can delay wound healing because there isn’t enough blood flow to the area. This can increase your risk of foot ulcers, which can become infected. In serious cases, you may need to have your foot amputated to stop the infection.

Do daily foot checks to detect foot issues early on. If you notice any redness, swelling, or sores, tell your healthcare team.

You may notice drainage seeping onto your socks or an unpleasant smell if you develop a foot ulcer.

6. You Notice Tingling and Numbness in Your Hands or Feet

Having high blood sugar over time can cause nerve damage, or diabetic neuropathy. This causes symptoms like tingling, numbness, weakness, and pain, and it most commonly presents in the hands, legs, and feet.

Some people may experience mild symptoms, while for others the symptoms can be very painful and significantly interfere with daily life. Nearly half of people with diabetes have diabetic neuropathy.

7. You Develop Blisters, Dryness, or Other Skin Changes

Having undiagnosed diabetes or diabetes that is not well managed can cause numerous skin changes. For example some people may notice numerous skin tags, excessive dryness, brown spots on the shins, yellow bumps on the eyelids, areas of hard, thickened skin or red-yellow waxy patches on the lower legs.

Dark, thick areas of soft skin (called acanthosis nigricans) may also form on the back of your neck or hands, armpits, face, or other areas. These can be a sign of insulin resistance, a hallmark of type 2 diabetes, Zanini says.

8. You Get Yeast Infections More Often Than Usual

The culprit of these infections is often a type of yeast (a fungus) known as Candida albicans.

“The yeast feeds off the glucose — and if your blood sugar is high, there’s more glucose in the urinary tract,” says Rahil Bandukwala, DO, an endocrinologist at MemorialCare South County Kidney and Endocrine Center in Laguna Hills, California. Uncircumcised men with high blood sugar have a higher risk of yeast infections, too.

“We’re also seeing [yeast infections] happen a little more now with patients who take SGLT2 inhibitors, which force the body to expel more glucose through the urine,” Dr. Bandukwala says. Examples of SGLT2 inhibitors include empagliflozin (Jardiance) and dapagliflozin (Farxiga).

9. You Have Swollen or Bleeding Gums

Gum disease, which causes swollen, red, and inflamed gums, is a complication of diabetes.

Your saliva contains glucose. And the more it has, the more there is to feed the bacteria that combine with food in your mouth to form plaque and cause gum disease.

If not treated, gum disease can lead to tooth loss, pus and ulcers between the gums, and pain when chewing.
Gum disease can also make diabetes harder to manage, causing inflammation and higher blood sugar levels.

When to Check Your Blood Sugar Levels

How frequently you should monitor your blood sugar is based on a number of factors, including whether you’re taking insulin or oral medications, how well your blood sugar is managed, and your age.

“In general, I tell my patients with type 2 diabetes whose blood sugar is controlled that they don’t need to check it every day,” Bandukwala says. “If they have a glucometer and they want to check it, then I will tell them they can do a paired reading once a week, which means a fasting (before eating) reading and then another reading one to two hours after a meal (postprandial).”

If you’re looking to avoid the pain associated with standard glucometers and the decisions about when to check your levels, consider talking with your doctor about a continuous glucose monitor (CGM). This medical device tracks your blood sugar in real time and sends measurements to your smartphone or other device. It can also identify patterns, which you can share with your doctor, and notify you if your blood sugar is too high or low.

A reasonable goal for many nonpregnant adults is an A1C level of less than 7 percent, which is an average blood sugar level of less than 154 mg/dL.
But if you’re an older adult, have other health complications, or are reliant on insulin, you may have less stringent goals. “It really becomes more important to just keep [levels] in the same place,” says Bandukwala. “Keeping A1C between 7.5 and 8.5 may be very reasonable for such a patient.” It’s important to speak to your own doctor to establish what blood sugar levels you should target.

The Takeaway

The symptoms of high blood sugar (hyperglycemia) include unusual thirst and hunger, fatigue, vision changes, infections, changes to the skin, and nerve damage in the hands and feet.
These complications will vary considerably from one person to another, and can develop slowly or rapidly.
Long-term high blood sugar can contribute to diabetes complications, including vision loss, kidney disease, neuropathy, and cardiovascular disease. It’s important to treat the symptoms of hyperglycemia as warning signs.
Managing your blood sugar is crucial. Ask your doctor how often you should monitor your blood sugar and what your target range should be.

Additional reporting by Diana Rodriguez and Andrea Peirce.