Updated 20 February 2017

What is diabetes?

There are three main types of diabetes, type 1, type 2 and gestational diabetes that all involve the body's improper use of glucose.


Diabetes mellitus, more commonly known as diabetes, refers to a metabolic disorder that affect the body's ability to properly regulate blood glucose levels.

Types of diabetes

There are different types of diabetes

1. Type 1 diabetes (due to β-cell destruction, usually leading to absolute insulin deficiency)

2. Type 2 diabetes (due to insulin resistance and progressive insulin secretory defects

3. Gestational diabetes mellitus (GDM) (diabetes diagnosed in the second or third trimester of pregnancy that is not clearly overt diabetes)

4. Specific types of diabetes due to other causes, e.g., monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young [MODY]), diseases of the exocrine pancreas (such as cystic fibrosis), and drug- or chemical-induced diabetes (such as in the treatment of HIV/Aids).

Secondary diabetes describe causes like chronic pancreatitis, cancer of the pancreas, iron overload disease affecting the pancreas (haemochromatosis) and a number of other secondary causes of pancreatic dysfunction resulting in an elevated blood sugar.

Sometimes it is difficult to assign a patient with certainty into type 1 or 2 diabetes or occasionally even secondary diabetes and this might depend on the clinical presentation of the disease and the progression of the disorder.

Type 1 and type 2 diabetes are systemic disorders, meaning that they affect many of the body's organs, tissues and systems. The extent of the damage caused to different areas of the body can be minimised through proper blood glucose, blood pressure and cholesterol control.

Regulating blood glucose

To maintain blood sugar in an acceptable range involves taking your medication regularly as prescribed, testing your blood glucose levels several times per day as advised by your doctor and by committing to healthy lifestyle choices including regular exercise, a well-balanced, healthy diabetic diet prescribed by a qualified dietitian, taking alcohol in moderation (if at all) and cessation of smoking.

Type 1 diabetes

Type 1 diabetes is an autoimmune disease that results in the destruction of the insulin-producing beta cells in the pancreas.

It is a progressive disease in that it worsens over time and eventually results in very little if any insulin production. As a result, type 1 diabetics start insulin treatment early on and need to take insulin for the rest of their lives in order to survive.

Insulin is usually administered via several injections per day or through the use of an insulin pump.

Type 1 diabetes is usually diagnosed in children and teenagers, although the number of adults diagnosed with the disease is increasing.

The long-term complications of type 1 diabetes can be well controlled by using a “tight-control” regimen in which blood glucose is measured several times each day and the insulin dose adjusted accordingly.

Low blood sugar (hypoglycaemia) must be avoided.

Type 2 diabetes

Type 2 diabetes is the most common variety of diabetes. Based on 2014 statistics, the World Health Organisation estimates that approximately 9% of people over the age of 18 suffer from the condition.

Type 2 diabetes is strongly associated with unhealthy lifestyle including poor diet, a sedentary lifestyle and obesity. There is also a significant genetic component to the disease.

Globally, people are generally consuming more processed, refined carbohydrates and exercising far less than they did a few decades ago. As result the number of people diagnosed with obesity and type 2 diabetes is increasing dramatically.

Initially, the person with this disorder develops an impaired tolerance to glucose, commonly known as insulin resistance. This means that the cells cannot properly absorb the insulin produced by the pancreas, resulting in high blood glucose levels after eating and eventually high blood glucose levels even when fasting.

Gestational diabetes

Gestational diabetes occurs during pregnancy and is a condition where the body cannot produce enough insulin. This happens because of extra weight and changing hormone levels.

Gestational diabetes can lead to serious complications, and both mother and child are at an increased risk to develop diabetes at a later stage in their lives.

Read more:

Symptoms of diabetes

Treating type 1 diabetes

Treating type 2 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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