Diabetes — both type 1 and type 2 — causes symptoms. Those with type 2 diabetes are less likely to notice symptoms until their blood sugar levels become very high. Those with type 1 diabetes are more likely to become symptomatic more quickly due to a lack of insulin.
Because those with type 2 diabetes are often asymptomatic until blood sugar levels are dangerously high, it is often thought of as a silent disease.
Common symptoms associated with diabetes include:
- Increased thirst
- Increased urination
- Increased hunger
- Unexplained weight loss
- Blurred vision
Polyuria, or excessive urination, can be caused by many medical conditions. These conditions include Cushing’s syndrome, pregnancy, liver disease, diabetes insipidus (which is unrelated to diabetes mellitus) and anxiety. It can also be an early symptom of kidney failure, as well as a side effect of various medications, such as corticosteroids, diuretics and lithium.
Polyuria occurs when glucose levels are very high. Normally, kidneys reabsorb glucose and direct it back into the bloodstream. When glucose is very high, the kidneys are unable to do that, causing excess glucose to remain in the urine. This causes excess urination.
Polydipsia, or excessive thirst, is often to a condition called psychogenic polydipsia, where people drink water when they do not need to. Occasionally, mental disorders, such as schizophrenia, anorexia, depression and anxiety, can cause polydipsia.
Polydipsia is also an indicator of hyperglycemia, or high blood sugar. This symptom is typically one of the earliest to develop, emerging slowly so that those who are suffering do not notice until it has become a problem.
Polydipsia typically begins to occur when glucose has been consistently elevated; when glucose is greater than 200 milligrams per deciliter, the kidneys are unable to pull the glucose from urine. This causes osmotic pressure changes, causing polyuria. As excess urination occurs, excess thirst also occurs due to dehydration.
Polyphagia is excessive hunger. Unlike increased hunger that may increase from excess exercise, polyphagia is insatiable — it does not go away when eating food.
There are various possible causes for polyphagia, such as hyperthyroidism, stress, lack of sleep and hypoglycemia (low blood sugar, which can also happen to people without diabetes). One of the main causes of polyphagia, however, is diabetes.
Polyphagia occurs when blood sugar levels are high. It occurs when glucose remains in the blood stream when there is a lack of insulin, such as with type 1 diabetes, or when the body is not using insulin effectively, such as with type 2 diabetes. Because glucose is remaining in the blood stream, the body has a lack of energy and the cells signal that the body needs energy; energy is taken in by consuming food.
Unexplained Weight Loss
There are many possible causes for unexplained weight loss; reviewing other symptomology is important when identifying the cause.
Unexplained weight loss occurs with uncontrolled blood sugar levels. As previously mentioned, lack of insulin inhibits the ability of cells to absorb glucose. Accordingly, cells are not getting the energy they need to function. To counteract this, the body starts burning fat and muscle for energy, resulting in rapid weight loss.
Fatigue can occur as a symptom from many illnesses and disease states. It is also a symptom of diabetes, particularly when blood sugar levels are very high.
Dehydration is extremely common when hyperglycemia occurs. This occurs due to the fluctuations in fluid volume. Fatigue is most likely to occur due dehydration.
Fatigue may also occur due to diabetes-related complications. For example, if diabetes has affected the liver, kidneys and heart and these organs are not working as well as they should, fatigue is likely to occur.
Hypothyroidism, or an underactive thyroid gland, is also common in those with diabetes. Hypothyroidism can cause fatigue.
Blurred vision is an extremely common symptom of diabetes, and is often reversible when glucose levels return to normal.
Hyperglycemia causes the lens of the eye to swell; this swelling causes blurry vision. Correcting this blurriness with a new pair of glasses is senseless as bringing glucose back to a target range will change the prescription.
However, blurred vision can also be a symptom of more serious eye problems.
- WebMD (What Is Polydipsia?)
- WebMD (Polyuria (Excessive Urine Production)
- WebMD (Diabetes and Blurred Vision)
- Timesulin (Why Does Diabetes Cause Excessive Thirst?)
- Mayo Clinic (Diabetes)
- JDRF (Polyuria and Type 1 Diabetes)
- Everyday Health (Why Does Type 2 Diabetes Make You Feel So Tired?)
- Healthline (7 Possible Causes for Polyphagia)