Type 1 diabetes

Type 1 diabetes is a condition where your body can't produce enough insulin - a hormone which regulates your blood sugar levels by allowing glucose to be absorbed into your cells for use or storage. It’s also known as Type 1 diabetes mellitus.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021

What is type 1 diabetes?

Type 1 diabetes is a lifelong condition and often starts in childhood or adolescence, although in some cases it can start in adulthood. Your genetics and certain viruses can increase your risk of developing type 1 diabetes. It affects around one in 10 people in the UK — that’s around 400,000 people.

It occurs due to a lack of the hormone insulin in your body, which is normally produced by your pancreas. Glucose gives you energy and helps your body function, and insulin allows glucose to be absorbed into your body’s cells. If your pancreas stops producing insulin or produces too little, glucose can’t be absorbed into your cells and therefore builds up in your bloodstream. This can make you feel exhausted and cause other long-term health problems. These include damage to your heart, eyes, feet and kidneys.

There is also a risk of serious acute health problems, such as:

  • Diabetic ketoacidosis — a build-up of substances called ketones in your blood
  • Hypers — when your blood sugar is too high
  • Hypos — when your blood sugar is too low

Type 1 diabetes usually develops quickly, in a matter of days or weeks, during which time your pancreas stops making insulin. Although it can’t be cured, your diabetes symptoms can be managed by monitoring your blood glucose levels, injecting insulin daily and eating a healthy diet. It can take time to adjust to this new lifestyle but you will then be able to enjoy all your usual activities. 

Type 1 and type 2 diabetes are different. Type 2 diabetes is associated with being overweight and is more likely as you get older — this is not true for type 1 diabetes. 

How to tell if you have type 1 diabetes

Signs of type 1 diabetes include feeling very tired, extremely thirsty and hungry, and changes in mood such as irritability. You might also need to urinate more than usual, especially at night — in children, they may start to wet the bed when they usually don’t. You may notice that cuts and grazes do not heal or take a long time to heal and find that your skin is itchy

Other type 1 diabetes symptoms include:

Symptoms can develop quickly, over just a few days or weeks, especially in children. If you’re worried about your symptoms, arrange to see your GP as soon as possible. 

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

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Diagnosis and tests for type 1 diabetes

Your GP will talk to you about your symptoms, and carry out a urine test and blood tests to check your glucose levels. The blood tests may include:

  • Fasting blood sugar test — this is performed after you’ve gone without food overnight
  • Glycated haemoglobin (HbA1c) test — this checks your average blood sugar levels over the past one to three months by measuring the part of your red blood cells that glucose attaches to
  • Random blood sugar test to check your glucose levels

If the tests show you have diabetes, your GP may carry out more tests to identify whether you have type 1 or type 2 diabetes.

If your GP suspects you have diabetes, they may recommend you go to hospital immediately to have these urine and blood tests. You may be asked to wait at the hospital to receive your results that same day.

Causes of type 1 diabetes

It is not known exactly why people get type 1 diabetes, although it is thought to be an autoimmune condition. 

Your immune system normally attacks germs that make you sick eg bacteria and viruses — one way it does this is by making antibodies that attach to these germs. 

However, in an autoimmune condition, your immune system mistakenly attacks healthy cells in your body. In type 1 diabetes, it makes antibodies against beta cells in your pancreas that produce insulin. These cells are destroyed and your pancreas stops making insulin. 

The role of insulin

Insulin is usually released into your bloodstream and allows your cells to absorb glucose (a sugar) from your bloodstream, which is needed to make energy. Insulin, therefore, lowers your blood sugar levels. As your blood sugar levels reduce, so too do the insulin levels in your blood. 

In type 1 diabetes, your blood sugar levels rise to damaging levels as there is no insulin to lower your blood sugar levels. 

The role of glucose

Your body gets glucose from two sources — the food you eat and your liver, where glycogen is broken down into glucose and released into your blood. If you have not eaten for a while, your liver will break down glycogen to help maintain a healthy level of blood sugar in your body.

Risk factors for type 1 diabetes

  • Age — type 1 diabetes usually starts in childhood, most often between the ages of four to seven and ages 10 to 14
  • Family history — if you have a first-degree relative (mother, father, sister, brother, son or daughter) with type 1 diabetes you have a one in 16 chance of developing it; this is higher than the risk of someone in the general population developing it, which is one in 300
  • Genetics — changes in certain genes increase your risk of type 1 diabetes
  • Geography — the prevalence of type 1 diabetes is higher in countries further away from the equator
  • Having a twin with type 1 diabetes

Common treatments for type 1 diabetes

Type 1 diabetes can’t be cured, however, it is still important to get treatment as soon as possible as it can be successfully managed. This will help you avoid serious, life-threatening complications and long-term health problems.

Aims of treatment

If you have high blood sugar levels, bringing them down to a healthy level, or as close as possible, will help you feel well again by reducing your symptoms. 

If your blood sugar levels rise again, becoming even slightly high, you can develop long-term health problems despite not having any short-term symptoms. Consequently, the more controlled your blood sugar levels, the lower your risk of health complications in the future, such as heart disease or eye problems. 

Treatment of type 1 diabetes therefore aims to:

  • Detect complications as soon as possible to ensure prompt treatment
  • Maintain your blood sugar levels as close to healthy levels as possible
  • Reduce other risk factors that together with your diabetes will increase your risk of complications eg reducing your blood pressure to prevent heart problems

Glucose monitoring

Your doctor will recommend that you monitor your blood sugar levels at home several times a day. You can do this using a blood glucose monitor. Aim to keep your blood sugar levels between four and seven mmol/L before meals and less than nine mmol/L two hours after a meal.

To do this, you will need to measure your blood glucose levels at different times in the day, particularly: 

  • After having a meal
  • During and after exercising
  • If you think you are becoming hypo

If you are unwell eg if you have a cold, infection or other illness, you should monitor your blood glucose levels more regularly as it can be harder to control your blood sugar levels. 

You will also need to have your blood glucose levels checked using an HbA1c blood test, which can be carried out by your GP or diabetes nurse. This will measure how well your blood glucose levels have been controlled over the previous one to three months. 

Keeping your blood sugar levels at a healthy level

Insulin injections

You will need to have insulin injections for the rest of your life to control your blood sugar levels. Insulin isn't absorbed by your gut, which is why you need to have injections directly into your bloodstream instead of taking tablets orally. Your doctor or diabetes nurse will give you clear instructions on how and when to inject yourself with insulin. They will also give you advice on how to adjust and cope with your treatment. 

There are different types of insulin. Your doctor will tailor a combination of insulin types that are most appropriate for you. The six main types of insulin are:

  • Long-acting analogue — this is injected once a day to maintain background insulin levels and lasts around 24 hours
  • Rapid-acting analogue — this can be injected just before, with or after food and lasts for two to five hours; it is only effective at controlling the glucose produced from the meal just eaten
  • Short-acting insulin — this is injected 15-30 minutes before a meal to control the increase in glucose immediately after eating; it lasts up to eight hours and is most effective two to six hours after injection
  • Medium-acting and long-acting insulin — these are injected one to two times a day to maintain background insulin levels and are sometimes used in combination with a rapid-acting analogue; they last up to 30 hours and are most effective four to 12 hours after injection
  • Mixed analogue — a combination of medium-acting insulin and a rapid-acting analogue
  • Mixed insulin — a combination of short-acting and medium-acting insulin

Most people with type 1 diabetes need to have insulin injections two to four times a day and often need to take different types and amounts each day depending on what they eat and their activity levels. 

When you first start having insulin injections, your doctor or diabetic nurse will recommend eating meals at set times so that you can take your injections at set times and doses. Once you are more familiar and confident with having insulin injections, you can discuss a more flexible plan with your care team. 

You will likely need to adjust your insulin injection routine as you get older and/or your body changes. Situations that will need you to change your insulin injection routine include: 

  • Being unwell
  • Losing or gaining weight
  • Stress
  • Taking other medications

Women with type 1 diabetes will also need to adjust their insulin injection routine according to their periods, if they get pregnant and when they go through menopause.

Insulin pumps

Insulin pumps continually pump fast-acting insulin into the layer of tissue just underneath your skin (subcutaneous tissue). The doses of insulin released by the pump vary throughout the day and night and are pre-set according to your particular needs. 

Managing the use of an insulin pump will take a lot of effort and motivation on your part. It, therefore, isn't suitable for everyone with type 1 diabetes. Your doctor will discuss what is needed to successfully use an insulin pump with you and whether it is suitable in your case. 

Eat a healthy diet

You do not need to eat special foods if you have type 1 diabetes but should follow a healthy diet, as is recommended for everyone to avoid ill health. 

Foods labelled as special diabetic foods will still raise your blood glucose levels and have as much fat and calories as other foods. They are also often more expensive than non-diabetic foods. You therefore do not need to buy diabetic foods. Instead, eat a diet with lots of fresh fruits, vegetables and fibre, and avoid high-fat, high-salt and high-sugar foods.

You will need to learn how to balance the dose of insulin you inject or set for your insulin pump with the amount of food you eat. A dietitian will teach you how to do this. It will involve knowing the amount of carbohydrates you eat and drink and matching your insulin dose to this. 

Carbohydrates are found in starchy foods, such as bread, pasta and rice ie starchy foods, as well as foods containing natural sugars, such as fruit, honey and milk. When you have an understanding of how to do this, you will no longer need to eat your meals and inject insulin at the same time every day and can instead follow a more flexible treatment plan. 

Reducing the risk of complications

Maintain a healthy blood pressure

Having type 1 diabetes and high blood pressure considerably increases your risk of other serious health complications. It is therefore important to have your blood pressure regularly checked. If it is even slightly high and you have diabetes, you will need to take blood pressure medications to treat it. 

Smoking increases your blood pressure and is linked to a host of other health complications, so you should quit as soon as possible. You can speak to your GP about support to help you quit smoking. 

To maintain a healthy blood pressure and reduce your risk of cardiovascular diseases, you should also regularly take part in physical activity, ideally at least 30 minutes every day. This can be as simple as going for a brisk walk every day, however, the more vigorous the exercise, the better eg cycling, dancing, jogging or swimming. Try to take part in an activity that leaves you a little out of breath and sweaty. 

Other medication

Your doctor may recommend taking medication to lower your cholesterol — this will depend on your age and how long you have had diabetes. Keeping your cholesterol within a healthy range will reduce your risk of complications such as heart disease and stroke.

Maintain a healthy weight 

If you are overweight or obese, it is important to lose excess weight as this puts you at greater risk of cardiovascular disease. Although you may not be able to reach your ideal weight, any excess weight you can lose will help. 

Get immunised

Make sure you get your annual flu vaccination and the pneumococcal vaccination. Both the flu and pneumococcal infection can be more serious if you have diabetes. 

Stay up to date with your health checks

Early detection of any complications will ensure you get treatment as soon as possible to prevent them becoming more serious. It is therefore important to have regular health checks. This may include appointments to: 

  • Check your blood pressure and have a blood test to check your average blood sugar levels over the previous one to three months (HbA1c test) and cholesterol 
  • Check your eyes for diabetic retinopathy, glaucoma and other eye diseases that you are at greater risk of developing because of your diabetes
  • Discuss your diet and lifestyle and provide appropriate advice
  • Have a blood test to check for kidney function, autoimmune diseases that are more common in people with diabetes (eg coeliac disease) and thyroid disorders
  • Have a urine test eg to check for proteins in your urine, which may suggest kidney problems
  • Have your feet checked to prevent foot ulcers and test sensation in your feet and legs to check for nerve damage

Look after your feet

Diabetes can reduce the blood flow to your feet and cause numbness. You are therefore less likely to notice if you have injured your foot and your foot may not heal as quickly or as well. This puts you at greater risk of infections and ulcers. 

It is therefore important to look after your feet by: 

  • Avoiding going barefoot outside to reduce the risk of cuts and grazes
  • Keeping them clean and dry to reduce the chances of infection
  • Wearing well-fitting shoes

You should also check your feet every day and if you notice any changes, let your GP or diabetes nurse know. Changes include: 

  • Blisters, cracks or cuts
  • Numbness
  • Pain 
  • Tingling

Check your vision

Diabetic retinopathy is an eye disease caused by diabetes damaging the blood vessels in your eyes. This can reduce your vision. You should have your eyes checked every year at a diabetic eye screening — this is different from a standard eye test. Diabetic eye screenings aim to detect damage to your eyes before it affects your vision. Prompt treatment can protect your vision. 

If you notice changes in your vision, let your GP know as soon as possible. Changes include: 

  • Blurred vision, particularly at night
  • Floaters in your vision — small, dark shapes floating across your vision, often described as cobwebs, spots or threads
  • Sensitivity to light

Emergency treatment

On any given day, if the balance between the food you have eaten, the physical exercise you have performed and the insulin you have injected is off, you may become hypo. This is when you develop hypoglycaemia ie too much insulin causes your blood sugar levels to drop too low. Symptoms of a hypo include confusion, feeling unwell and sweating.

If a hypo is untreated, you can go into a coma. Emergency treatment is therefore needed. This involves eating sugar, having a sugary drink or getting a glucagon injection — glucagon is a hormone with the opposite effect of insulin ie glucagon increases your blood sugar levels. You should then eat some starchy food eg a sandwich. 

Supporting you through your treatment

Treatment for type 1 diabetes can ensure you continue to lead a full life. At Spire Healthcare, we understand how daunting it can be to adjust to insulin injections or pumps, as well as all the lifestyle changes and additional monitoring you will need. Our healthcare team is here to support you every step of the way through all the changes ahead. 

Type 1 diabetes complications

Complications of type 1 diabetes can be both short-term and long-term. Long-term complications include damage to your blood vessels and nerves, and to your organs, including eyes, heart and kidneys. Maintaining healthy blood sugar levels is essential to reduce your risk of serious complications, which can become life-threatening or lead to disability. 

Complications include: 

Hypos (hypoglycaemia)

If your blood sugar levels drop too low (usually below four mmol/L) you will become hypo. This can happen if you: 

  • Delay eating your meals
  • Didn't eat enough carbohydrate in your last meal 
  • Drink alcohol without eating beforehand
  • Perform a lot of exercise without reducing your insulin dose or without eating the right amount of carbohydrate beforehand
  • Take too much insulin

Hypos come on very quickly and need immediate treatment. Watch out for the following signs: 

  • Being anxious or irritable
  • Blurred vision
  • Feeling hungry
  • Shaking or trembling
  • Sweating
  • Struggling to concentrate

If you notice signs of a hypo, get treatment quickly by eating or drinking something sugary, such as: 

  • A glass of a non-diet sugary drink eg cola
  • A glass of fruit juice
  • Five small sweets eg jelly babies
  • Three dextrose or glucose sweets

Hypers (hyperglycaemia)

If your blood sugar levels rise too high you can become hyper. This can happen if you: 

  • Are less active than usual
  • Are stressed
  • Are unwell
  • Did not take enough insulin for the amount of carbohydrate you ate in your last meal

Speak to your care team as soon as possible if you notice signs of hyperglycaemia, which include: 

  • Blurred vision
  • Feeling very thirsty
  • Fruity-smelling breath
  • Persistent tiredness
  • Unintentional weight loss
  • Urinating more than usual

If your blood sugar levels become too high you can develop diabetic ketoacidosis where your body begins to break down fat for energy. This causes acid (ketones) to accumulate in your blood and is potentially life-threatening. You will need urgent treatment at hospital. 

Cardiovascular disease

Diabetes greatly increases your risk of diseases affecting your heart and blood vessels. This includes angina, coronary artery disease, heart attack, high blood pressure, narrowing of your arteries (atherosclerosis) and stroke.

Nerve damage 

High blood sugar levels can damage the walls of tiny blood vessels (capillaries) that supply oxygen and nutrients to your nerves. 

This most often occurs to nerves in the legs, causing a burning sensation, numbness, tingling and/or pain that starts at the tips of your toes and radiates upward. In severe cases, your affected limbs may eventually become completely numb.

Damage to nerves in your gut can cause diarrhoea or constipation, nausea and vomiting

For men, nerve damage may cause erectile dysfunction.

Kidney damage 

High blood sugar levels can damage the walls of the network of blood vessels in your kidneys, which help filter waste from your blood. Diabetes can therefore cause kidney failure or end-stage kidney disease — treatment involves dialysis or a kidney transplant.

Eye damage

High blood sugar levels can damage the blood vessels that supply the backs of your eyes (retina) causing the eye disease diabetic retinopathy, which can result in blindness if left untreated. Diabetes also increases your risk of other eye conditions, including cataracts and glaucoma.

Foot damage

Diabetes can damage the nerves in your feet and reduce blood flow to your feet. This increases the risk of complications, such as blisters, cuts and scrapes that do not heal and become infected. Left untreated, such injuries can put you at risk of needing toe, foot or leg amputation. 

Skin and mouth conditions

Diabetes increases your risk of skin and mouth infections caused by bacteria and fungi. You are also more likely to develop gum disease and dry mouth.

Pregnancy complications

High blood sugar levels during pregnancy are dangerous for the mother and unborn baby. It increases the risk of birth defects, miscarriage and stillbirth. In the mother, it also increases the risk of diabetic ketoacidosis, eye diseases such as diabetic retinopathy, pregnancy-induced high blood pressure and preeclampsia.

Living with type 1 diabetes

Drinking and drugs

Living with type 1 diabetes will affect many aspects of your life, notably drinking and eating. While you can still drink alcohol, drinking too much can trigger a hypo even up to 24 hours later. If you’re planning on drinking alcohol, you can take steps to reduce your risk of a hypo by: 

  • Checking your blood sugar levels — check it before you go to bed and regularly the day after as a hypo can feel similar to a hangover
  • Diluting your alcohol intake with diet soft drink mixers
  • Drinking lots of water the next day 
  • Eating a carbohydrate-rich meal before you drink eg rice or pasta
  • Eating a sugary snack if your blood sugar levels are low
  • Ensuring the people you are socialising with know the signs of a hypo 

Using recreational drugs may affect your ability to think clearly and manage your blood sugar levels. It is therefore advised that you do not take any recreational drugs if you are diabetic. 

Exercise and sport

Exercise and sport are an important part of living a healthy lifestyle and you can continue to enjoy both with type 1 diabetes. However, you need to pay close attention to how it affects your blood sugar levels. Some types of exercise and sports will increase your blood sugar levels, while others will decrease them.

If you're planning to exercise, you can take steps to help control your blood sugar levels. This includes: 

  • Checking your blood sugar levels before, during and after exercise — this will help you determine what to eat and how to adjust your insulin; you may need to regularly check your blood sugar levels after exercise as they can drop up to 12 hours afterwards, which means you may need to eat extra carbohydrate or reduce your insulin dose before bedtime
  • Drinking lots of water when you exercise
  • Keeping a record of your blood sugar levels and what you eat whenever you exercise and showing this to your diabetes nurse or doctor — together you then develop a plan to better control your blood sugar levels
  • Making sure you have extra carbohydrate at hand to prevent hypos

Travel and driving

There are no restrictions on travelling if you have diabetes. However, you need to make preparations to avoid problems eg packing extra insulin doses. 

If you have diabetes and drive, you are legally required to: 

  • Check your blood sugar levels before your drive — no earlier than two hours before
  • Check your blood sugar levels every two hours on long journeys
  • Travel with sugary snacks and snacks with long-lasting carbohydrates (low glycemic index carbohydrates) eg cereal bars or bananas

Type 1 diabetes and coronavirus

Diabetes does not increase your risk of catching coronavirus. However, if you do become infected with coronavirus and have any type of diabetes, you are at greater risk of becoming seriously unwell. Other risk factors for developing a serious illness from coronavirus include: 

  • Being black, Asian or minority ethnic 
  • Being obese ie having a body mass index over 30
  • Being older 
  • Health complications such as heart failure or kidney disease
  • Poorly controlled blood sugar levels ie history of high HbA1c (as determined by a Hb1Ac blood test)

However, it is important to remember that most cases of coronavirus only cause mild symptoms, if any. The way coronavirus affects people varies considerably, and in children, the risk of serious illness is very low. 

Being unwell, whether due to coronavirus or another infection, can make it harder to control your blood sugar levels. This is because your body releases sugar into your blood to give you the energy to fight the infection. However, if you have type 1 diabetes, your body can't release enough insulin to bring your blood sugar levels back down. This makes it harder to control your diabetes when you’re ill and puts you at greater risk of hypos and hypers. 

In extreme cases of high or low blood sugar, you can develop serious conditions such as diabetic ketoacidosis or hyperosmolar hyperglycaemic state.  

If you get coronavirus, follow your sick day rules for managing your blood sugar levels. 

Frequently asked questions

What is the difference between type 1 and type 2 diabetes?

Type 1 diabetes occurs when the cells in your pancreas that make insulin are destroyed. However, in type 2 diabetes, these cells are still present and continue to make insulin but can’t make enough or the insulin that is made doesn’t work properly. Symptoms of type 1 diabetes usually come on quickly, in days or weeks, while symptoms of type 2 diabetes can take years to develop and may initially go unnoticed. While both types of diabetes can affect you at any age, type 1 diabetes more commonly starts in childhood while type 2 diabetes tends to start in adulthood.

Which is worse, type 1 or 2 diabetes?

Both types of diabetes pose a threat to your health. If either is left untreated, the high blood sugar levels can cause short-term and long-term health problems, which in some cases can be life-threatening.

Is type 1 diabetes genetic?

It isn’t yet known exactly what causes type 1 diabetes. However, it can run in families, which suggests genetics are involved. If you have a mother, father, sister, brother, son or daughter with type 1 diabetes, then you have a one in 16 chance of also developing it. This is much higher than the average risk of developing diabetes in the general population which is one in 300. Scientists have also identified changes in certain genes that increase your risk of type 1 diabetes.

Can type 1 diabetes be reversed?

No, type 1 diabetes can’t be reversed as the cells in the pancreas that produce insulin are permanently destroyed. However, its symptoms can be effectively managed by taking insulin and making lifestyle changes.

Can type 1 diabetes come on suddenly?

Type 1 diabetes usually comes on suddenly, in days or weeks. If you notice symptoms of type 1 diabetes, see your GP as soon as possible.

Is type 1 diabetes avoidable?

Type 1 diabetes is not avoidable and it isn’t clear what causes it, although genetics are thought to be involved.

What is the oldest age you can get type 1 diabetes?

According to data collected by the National Diabetes Audit, one in five cases of type 1 diabetes is diagnosed in the over 40s — this included one in 20 cases diagnosed in those aged over 69.

How long can you live with type 1 diabetes?

Improved treatments and management of type 1 diabetes means the life expectancy for those with the condition has increased considerably over the years.

There was a time when the average life expectancy of someone with type 1 diabetes was around 20 years shorter than the national average, according to Diabetes UK. This is no longer the case.

While the life expectancy of a person with diabetes is still on average slightly lower than the national average, with proper treatment and lifestyle changes, a person with diabetes can live a full life.

What viruses can trigger type 1 diabetes?

The main group of viruses linked to triggering type 1 diabetes is enteroviruses, such as coxsackievirus B. However, other viruses have also been linked to the condition, including rotavirus, mumps virus and cytomegalovirus.

What should type 1 diabetics not eat?

If you have type 1 diabetes, you do not need to eat special diabetic foods. However, you should follow a healthy, balanced diet, rich in fibre, fruits and vegetables. You should also avoid high-fat, high-sugar and high-salt foods. Most importantly, you need to learn how to balance what you eat with how much insulin you need to take and when. Your diabetes nurse or doctor, or a dietitian can advise you on this. 

Does type 1 diabetes lower your immune system?

Type 1 diabetes is an autoimmune disorder, where your immune system mistakenly attacks and destroys insulin-producing cells in your pancreas. However, it does not cause other healthy cells or tissues to be destroyed by your immune system. If your blood sugar levels are well-controlled, type 1 diabetes does not impair your immune system.

Do type 1 diabetics get sick more often?

If you have type 1 diabetes and your blood sugar levels are well-controlled you are not more likely to get sick. However, if your blood sugar levels are not well-controlled, cuts and scrapes may not heal properly and you will be more prone to infections. 

How can I boost my immune system with type 1 diabetes?

Whether or not you have diabetes, you can support your immune system by eating a healthy, balanced diet to ensure you get all the nutrients and vitamins you need, as well as taking part in regular exercise. If you have diabetes and take part in exercise, you will need to factor in how this will affect your blood sugar levels and adjust your meals and insulin accordingly.