Diabetes: the basics

What is diabetes?

Diabetes is a disease caused by high levels of sugar (glucose) in the blood. It is becoming more common as people live more comfortably, eat richer food and move less.

The body's cells need energy, which comes from the sugar in our food. Sugar passes into the blood and then into the cells, but it can only get into the cells with the help of insulin. When there isn't enough insulin, or the cells don't respond to it, sugar builds up in the blood while the cells go short and "hungry". This signals a need for sugar, so the person eats sweet foods, which raises blood sugar further, and the problem gets worse.

Diabetes can be controlled with diet, exercise and the right medicines. But if it is ignored because it doesn't hurt, it leads to serious complications such as blindness, nerve and kidney damage, heart and blood vessel disease, and death.

Types of diabetes

Type 1 diabetes, also called juvenile or insulin-dependent diabetes, starts at a young age, usually in people of normal or low weight. Patients always need insulin, because their body no longer makes it (the immune system destroys the cells that produce it). It often runs in families.

Type 2 diabetes, once called adult-onset diabetes, affects older people, who are often overweight. Insulin is present in the blood, but the cells resist it. Patients usually manage it with diet and tablets, though some later need insulin.

Treatment

Treatment includes diet, exercise and medicines.

Diet: it's important to control total calories, not just sugar, because fats and proteins also affect blood sugar. The brain and red blood cells rely mainly on sugar for energy, so don't cut carbohydrates out, but don't overdo starches or fats either. The diet should be balanced, with moderate protein. Foods with the same calories don't all raise blood sugar equally: pasta, for example, raises it less than toast, so it's useful to know how much different foods raise blood sugar (their glycaemic index).

Exercise: people with diabetes are advised to exercise and lose weight, especially in type 2 diabetes. But too much exercise can cause harm and low blood sugar, so choose exercise that suits you and increase it gradually. Exercise boosts the effect of insulin, so the insulin dose may need lowering. Don't exercise for long periods without eating, and avoid big meals just before exercise; exercise some time after a moderate meal, and keep something sugary to hand in case of a low.

Medicines: patients usually start with tablets that lower blood sugar, and later may need insulin. Blood sugar needs regular monitoring and doses need adjusting, because a severe low can cause coma and can kill. It is wrong to see insulin as an enemy or a sign that things are bad: insulin helps people with diabetes enjoy life and carry on with their daily activities.

Complications

Studies show that treatment helps prevent complications, but always watch out for low blood sugar: check your levels and adjust doses as needed. Complications include:

Eye disease: retinopathy, which can cause blindness; cataracts and glaucoma are also more common, especially in type 2 diabetes.
Nerve damage: including the cranial nerves and the nerves of the trunk and thighs.
Heart and blood vessel disease.
Kidney disease: in 35–45% of people with type 1 diabetes and about 20% with type 2.
Urinary, sexual and digestive problems.
Diabetic foot: small wounds are rich in sugar, which feeds germs, and nerve damage reduces pain, so wounds may go unnoticed and turn into ulcers that can end in amputation.

People with diabetes should avoid tight shoes, check their feet regularly, wash them every day and look after any wound or change at once.