Updated 20 February 2017

Symptoms of diabetes

Symptoms of diabetes include excessive thirst, increased urination, weight loss and fatigue. It is important to recognise these symptoms as, left untreated, diabetes can cause coma and even death


The classical symptoms of diabetes include excessive thirst, increased urination, weight loss and fatigue. It is important to recognise these symptoms as, left untreated, diabetes can cause coma and even death.

These symptoms are mainly found in type 1 diabetes. For most type 2 diabetics, the condition is quite often asymptomatic and found coincidently at a visit to the doctor for some other reason, or at a life assurance medical check or after developing a complication of the disease.

Symptoms of type 1 diabetes

The most common symptoms of type 1 diabetes are:

- Excessive thirst

 - Increased urination

- Fatigue

- Blurred vision

- Weight loss

- Tiredness

These symptoms can occur abruptly over a few days. However, the first sign of type 1 diabetes can also be a coma, or near coma, as a result of an event called diabetic ketoacidosis in which the levels of glucose in the blood are so high that this life-threatening state occurs.

Due to a lack of insulin, the glucose in the blood cannot enter the cells where it is desperately needed. To prevent starvation and cell death, lipids are metabolised to ketones.

Ketones can be used as food by the cells, for example cells in the brain, even in the absence of insulin. Ketones can however be dangerous because they are acidic in nature and cause acidosis.

The condition is called ketoacidosis and is the result of insulin deficiency in type 1 diabetics. 

Clinically patients feel unwell. They might have nausea and vomiting and loss of appetite.

They urinate excessively, and if the condition is not recognised and treated urgently, the person becomes drowsy and eventually comatose.

This might be in response to an infection, surgery or stress or occur spontaneously. The hallmark of diabetic ketoacidosis is the presence of ketones in the urine.

The level of insulin in the blood will be low or undetectable.

Symptoms of type 2 diabetes

This condition is mostly asymptomatic (no symptoms).

Often the diagnosis is made coincidentally, or after the patient presents with a complication caused by the condition. Symptoms of type 2 diabetes, when they do occur, might be similar to the symptoms found in type 1 diabetes, but not as severe:

- Excessive thirst

- Increased urination

- Blurred vision

- Weight loss

- Fatigue

Early in the course of the disease there might be subtle signs such as greater susceptibility to infection, poor wound healing, and fatigue. An early sign in men is occasional erectile dysfunction.

Candida infection of the tip of the penis (Candida balanitis) is also common. In women, persistent vaginal Candida may be an early sign of type 2 diabetes, particularly in older women.

Symptoms of gestational diabetes

Gestational diabetes is not usually associated with any symptoms, but pregnant women do need to be tested – usually at the first pre-natal visit and then again between week 24 and 28.

Classical signs of diabetes are often confused with symptoms common to pregnancy, for example, fatigue and frequency of urinating (micturition). Some pregnant women might have had type 2 diabetes before their pregnancy without having been aware of it.

Read more:

What is diabetes?

Diagnosing diabetes

Causes of diabetes

Reviewed by Dr Hilton Kaplan, MB BCH (Rand), FCP(SA), MMed(UCT), Specialist Endocrinologist and Physician (March 2016)


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Dr. May currently works as a fulltime endocrinologist and has been in private practice since 2004. He has a variety of interests, predominantly obesity and diabetes, but also sees patients with osteoporosis, thyroid disorders, men's health disorders, pituitary and adrenal disorders, polycystic ovaries, and disorders of growth. He is a leading member of several obesity and diabetes societies and runs a trial centre for new drugs.

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