Unexplained Sudden Weight Loss, Constant Hunger, and Fatigue

Reviewed by: HU Medical Review Board | Last reviewed: October 2020.

Unexplained sudden weight loss, constant hunger, and fatigue (extreme tiredness) can be signs that your blood glucose (sugar) is too high.

In type 2 diabetes, your body is resistant to insulin and eventually, it does not make enough. Insulin is a hormone that helps glucose, also known as sugar, get into cells to be used for energy. Because there is not enough insulin to help this process, too much glucose stays in the blood.1

Sudden weight loss, constant hunger, and fatigue are serious symptoms that should be addressed with your doctor. They can be a sign of diabetic ketoacidosis, a dangerous, short-term complication of diabetes. Recognizing these symptoms can help you get the right treatment sooner.

Why does diabetes cause sudden weight loss, constant hunger, and fatigue?

Your body gets energy from glucose that is in the foods you eat. In type 2 diabetes, your body is not able to use the glucose effectively. This causes your blood glucose levels to become too high. This can lead to constant hunger. Your body may start burning fat and muscle for energy instead, which can cause rapid weight loss.1,2

Weight loss can also be caused by frequent urination, which is another common symptom of type 2 diabetes. This happens in type 2 diabetes when extra glucose and other fluids from your organs are removed in your urine. This process can make you dehydrated and leave you feeling extra thirsty. This causes you to drink more fluids to quench your thirst, which leads to even more urination.2

Dehydration from excessive urination can also lead to feelings of fatigue. High blood sugar is another cause of fatigue since your body cannot use the glucose for energy. Studies have found that fatigue in people with type 2 diabetes may also be a result of chronic inflammation caused by a weakened immune system.3

What should I do if I experience these unexplained symptoms?

If you experience these common symptoms but have not been diagnosed with type 2 diabetes, you should see your doctor and discuss what you are experiencing. Talk to your doctor about measuring your blood glucose to determine if it is high and whether you may have diabetes.

If you have already been diagnosed with type 2 diabetes, unexplained sudden weight loss, constant hunger, and fatigue are signs that your blood glucose levels are not under control. You should contact your doctor right away about these symptoms, especially if you have signs of diabetic ketoacidosis (DKA).4

What is diabetic ketoacidosis?

DKA is a serious, short-term complication of diabetes. It occurs when your body has high blood glucose and a buildup of blood acids called ketones. Since people with type 2 diabetes do not produce enough insulin so their body can use glucose for energy, their body may burn fat instead to get energy. Burning fat causes the production of ketones, which can be toxic in the bloodstream.4-6

DKA most commonly occurs in people who are sick with nausea, vomiting, and not eating. Therefore they do not take their insulin. It can also occur in people who do not know they have diabetes and their pancreas has already failed to produce the necessary amount of insulin. Illness also increases your need for insulin because blood sugar rises as your body’s response. Symptoms of diabetic ketoacidosis usually develop quickly, and in extreme cases can cause a person to go into a coma. It should be treated as a medical emergency. If you experience symptoms of ketoacidosis, call your doctor right away.4-6

While maintaining a healthy weight is a healthy part of type 2 diabetes management, it is important to note that rapid, unexplained weight loss requires immediate medical attention.

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