If diabetes isn't treated, it can lead to a number of other health problems.

High glucose levels can damage blood vessels, nerves and organs.

Even a mildly raised glucose level that doesn't cause any symptoms can have long-term damaging effects.

Heart disease and stroke

If you have diabetes, you're up to five times more likely to develop heart disease or have a stroke.

Prolonged, poorly controlled blood glucose levels increase the likelihood of atherosclerosis (where the blood vessels become clogged up and narrowed by fatty substances).

This may result in poor blood supply to your heart, causing angina (a dull, heavy or tight pain in the chest). It also increases the chance that a blood vessel in your heart or brain will become blocked, leading to a heart attack or stroke.

Nerve damage

High blood glucose levels can damage the tiny blood vessels in your nerves. This can cause a tingling or burning pain that spreads from your fingers and toes up through your limbs. It can also cause numbness, which can lead to ulceration of the feet.

Damage to the peripheral nervous system, which includes all parts of the nervous system that lie outside the central nervous system, is known as peripheral neuropathy.

If the nerves in your digestive system are affected, you may experience nausea, vomiting, diarrhoea or constipation.

Diabetic retinopathy

Diabetic retinopathy is when the retina (the light-sensitive layer of tissue at the back of the eye) becomes damaged. Blood vessels in the retina can become blocked or leaky or can grow haphazardly. This prevents light from fully passing through to your retina. If it isn't treated, it can damage your vision.

Annual eye checks are usually organised by a regional photographic unit. If significant damage is detected, you may be referred to an ophthalmologist (a doctor who specialises in treating eye conditions).

The better you control your blood glucose levels, the lower your risk of developing serious eye problems.

Diabetic retinopathy can be managed using laser treatment if it's caught early enough. However, this will only preserve the sight you have rather than improve it.

Kidney disease

If the small blood vessels of your kidney become blocked and leaky, your kidneys will work less efficiently. It's usually associated with high blood pressure, and treating this is a key part of management.

In rare, severe cases, kidney disease can lead to kidney failure, and a kidney replacement treatment with dialysis, or sometimes kidney transplantation, will be necessary.

Foot problems

Damage to the nerves of the foot can mean small nicks and cuts aren't noticed, and this, in combination with poor circulation, can lead to a foot ulcer.

About 1 in 10 people with diabetes get a foot ulcer, which can cause a serious infection.

If you have diabetes, look out for sores and cuts that don't heal, puffiness or swelling, and skin that feels hot to the touch. You should also have your feet examined at least once a year.

If poor circulation or nerve damage is detected, check your feet every day and report any changes to your doctor, nurse or podiatrist (foot care specialist).

Read more about foot care and diabetes.

Sexual dysfunction

In men with diabetes, particularly those who smoke, nerve and blood vessel damage can lead to erection problems. This can usually be treated with medication.

Women with diabetes may experience:

• a reduced sex drive (loss of libido)
• less pleasure from sex
• vaginal dryness
• less ability to orgasm
• pain during sex

If you experience a lack of vaginal lubrication, or you find sex painful, you can use a vaginal lubricant or a water-based gel.

Miscarriage and stillbirth

Pregnant women with diabetes have an increased risk of miscarriage and stillbirth. If your blood glucose level isn't carefully controlled during the early stages of pregnancy, there's also an increased risk of the baby developing a birth defect.

Pregnant women with diabetes will usually have their antenatal check-ups in hospital or a diabetic clinic, ideally with an obstetrician (a doctor who specialises in pregnancy care).

This will allow your care team to keep a close eye on your blood glucose levels and control your insulin dosage more easily, as well as monitoring the growth and development of your baby.

The Diabetes UK website has more information about diabetes complications.