The increased incidence of obesity in the Western world is thought to be the biggest single factor in the rise in the number of people being diagnosed with type 2 diabetes.

What is obesity?

Obesity can be thought of as being dangerously overweight, and is clinically defined as having a body mass index (BMI) of over 30. A BMI of over 40 is usually classed as morbid obesity. Waist size may be an even better indicator of obesity and its potential impact on health. Having a waist larger than 102 cm if you are a man, or 88 cm if you are a woman means you are obese.

Obesity brings many problems, including an increased risk of developing:

  • Type 2 diabetes.
  • High blood pressure.
  • Heart disease.
  • Obstructive sleep apnoea (OSA).
  • Liver disease, including fatty liver and non-alcoholic steatohepatitis, which can lead to cirrhosis of the liver.
  • Joint problems.
  • Skin problems.

What is type 2 diabetes?

If you are healthy, the level of glucose in your blood is controlled very tightly by hormones. If the blood glucose level rises, which it does shortly after you have eaten, the body responds by releasing insulin. Insulin circulates around the body and stimulates body cells to absorb glucose. The cells get the glucose they need to fuel metabolic reactions and the blood level of glucose falls and returns to normal.

Blood glucose levels need to be kept within tight limits; if it rises or falls too far, this causes either:

  • Hyperglycaemia: when the blood glucose is too high. When this happens over a long period of time it causes damage to tissues and organs, causing the common complications of badly controlled diabetes.
  • Hypoglycaemia: if your blood glucose falls, you feel faint, weak and dizzy and eventually may fall into a coma.

In type 1 diabetes the body makes little or no insulin so treatment involves replacing the missing hormone. In type 2 diabetes, the body usually makes insulin but the cells stop responding, a problem known as insulin resistance. Insulin resistance is a common consequence of obesity. Treatment of type 2 diabetes, particularly in the early stages, may therefore not involve insulin injections.

Why do obese people get type 2 diabetes?

The exact reason is poorly understood and is the subject of much research. It seems that above a certain body weight, the level of fat in the body leads to metabolic and hormonal changes that make cells less receptive to insulin.

Problems faced by people who have obesity and diabetes

The complications associated with diabetes are well-known, and many of them are exacerbated by obesity. It is important that people with diabetes are aware of the likely complications so that early detection and treatment is possible.

Poorly controlled diabetes can lead to deterioration of blood vessels, and the greater the fluctuations in blood glucose, the greater the damage. Small, delicate blood vessels tend to be damaged first and this is the underlying cause of many of the following problems:

  • Heart disease and stroke. The coronary blood vessels that supply the heart with blood can become narrower, leading to a heart attack, and narrowing in the carotid arteries can lead to stroke.
  • Diabetic retinopathy. The blood vessels of the retina become damaged and this can lead to sight loss.
  • Kidney problems. The tiny blood vessels that surround the kidney tubules can become damaged, reducing the kidney’s ability to filter the blood efficiently. This condition is often called diabetic nephropathy.
  • Nerve damage (diabetic neuropathy). The small blood vessels that supply nerves can be disrupted, leading to problems with nerve function.
  • Foot ulcers nerve damage can mean that cuts and grazes go un-noticed and become infected. The poor blood supply means that infections are slow to heal. Consequently, diabetes is the leading cause of lower leg amputations worldwide.
  • Sexual problems. Erectile dysfunction is common, while women may experience a reduced sex drive, vaginal dryness and find sex painful.  

Pregnant women who were obese before they conceived and who have type 2 diabetes or gestational diabetes are more likely to lose their baby through a miscarriage or to have a stillborn child. Women who develop diabetes in pregnancy are more likely to develop type 2 diabetes later in life.