Diabetes is a common, life-long condition in which the level of sugar (glucose) in your blood is too high. If untreated, it can cause many serious – even life-threatening – health problems. Diabetes can, however, be controlled with lifestyle changes and medication.

What is diabetes?

Diabetes is the general name for a group of disorders in which the amount of glucose (sugar) in your bloodstream is too high because your body can’t convert it into energy.  Cells throughout your body need glucose for energy but also need a hormone called insulin to let them use it. In diabetes, you either make too little insulin, or your cells don’t react properly to your insulin, or both. 

Having too much glucose in your blood (hyperglycaemia) can damage many parts of the body, including your heart, kidneys, blood vessels, nerves, eyes and hearing. These complications can eventually become disabling or even fatal. Diabetes is a progressive disease, meaning it’s likely to get worse over time. However, with proper control of your blood glucose level it is possible to slow or even halt the progression and avoid many complications.

According to the US Centers for Disease Control and Prevention, 30.3 million Americans – 9.4% of the U.S. population – had diabetes in 2015. Of those, 7.2 million were unaware they had the condition. In the UK, 2017 figures show 3.7 million people living with diagnosed diabetes, and a further 1 million having the condition without being aware of it.

Types of diabetes

Diabetes is formally called diabetes mellitus (DM) and there are two main types – type 1 and type 2 – along with several rarer conditions.

People with type 1 diabetes lose the ability to make insulin, which is produced in the pancreas, a large gland behind the stomach. It’s an ‘autoimmune’ disease in which your own immune system attacks and destroys the cells that make insulin. With no insulin, the cells can’t use glucose from the blood.

Type 2 diabetes develops when your pancreas, though working, can’t produce enough insulin, or your cells don’t respond to the insulin. Again, this means glucose in your blood can’t be used as fuel and instead builds up in your bloodstream. 

Other forms of the condition include gestational diabetes, which affects up to 5% of pregnant women; it usually goes away after the birth but increases the woman’s risk of later developing type 2 diabetes. Rarer types of diabetes include maturity-onset diabetes of the young (MODY), neonatal diabetes, Wolfram syndrome and Alström syndrome.

This information is mainly about type 2 diabetes, which accounts for 90 per cent of all cases.

What are the symptoms of diabetes?

Symptoms of diabetes include being continually very thirsty, urinating more than usual, and feeling constantly tired or fatigued.

When the level of glucose in your blood is too high your body tries to get rid of it in your urine, which makes you go more often. You feel tired because you can’t get the energy you need from the glucose.

Symptoms of both type 1 and type 2 diabetes are similar. In type 1 they appear rapidly, generally over a few weeks, and it’s usually obvious something is wrong. In type 2 diabetes symptoms appear gradually, often over several years, and can be hard to spot.

The main symptoms include:

  • urinating often, especially at night 
  • being thirsty
  • being tired
  • having blurred vision
  • losing weight for no obvious reason
  • having genital itching or episodes of the yeast infection thrush
  • having cuts, grazes or sores that heal only slowly
  • feeling numbness or tingling in toes or fingers

Symptoms of type 2 diabetes can be so mild that you might not even notice them. Many people with type 2 diabetes have no symptoms and the condition is discovered only in a routine check-up. Some people don’t know they have the disease until it has caused another problem, such as heart trouble.

Anyone with symptoms should have them checked out – early diagnosis gives you the best chance of controlling diabetes.

How is diabetes diagnosed?

Many people find out they have type 2 diabetes during routine check-ups or when other complaints are being investigated. Urine and blood tests can detect high blood glucose and several specialized blood tests can be used to diagnose and monitor diabetes. 

Often the first indication that you might have diabetes comes from a urine test. Urine usually doesn’t contain glucose, but if you have diabetes, your kidneys try to get rid of the glucose through your urine. 

If you have glucose in your urine, further tests can be used to discover if you have diabetes. One high blood glucose reading won’t immediately lead to a diabetes diagnosis – usually at least two separate tests on different occasions are needed.

The concentration of blood glucose is generally given either as mg/dL (milligrams per deciliter) or mmol/L (millimoles per litre – the number of molecules in a litre). In the US, mg/dl is the norm, whereas mmol/L is most commonly used in the UK. Some results are given as percentages or millimoles per mole – a mole is a unit of chemical mass.

Tests that can be used to diagnose diabetes include:

HbA1c test – also called a glycated haemoglobin test or A1C test, this measures your average blood glucose level over the past few months. A result below 5.7% is normal, between 5.7% and 6.4% suggests prediabetes, and 6.5% or above indicates diabetes. 

Glucose tolerance test (GTT) – your blood sugar levels are tested before and then a couple hours after you take a glucose drink. It’s a ‘fasting’ test, so you can’t eat for 8-12 hours beforehand, usually overnight. Two hours after the drink, a blood sugar level of 140mg/dL (7.8mmol/L) or below is normal, 140 to 199mg/dL indicates you have prediabetes, and 200mg/dL (11mmol/L) or above indicates diabetes.

Fasting blood sugar test – this measures your blood sugar after not eating for 8 or more hours – usually overnight. A fasting blood sugar level of 99mg/dL (5.5mmol/L) or lower is normal, 100 to 125mg/dL is regarded as pre-diabetes, and 126mg/dL (7mmol/L) or higher indicates diabetes.

Random Blood Sugar Test
This measures blood sugar at the time you’re tested. You don’t need to fast beforehand. A blood sugar level of 200mg/dL (11mmol/L) or above indicates diabetes.

What causes diabetes?

It’s not certain precisely what causes type 2 diabetes but a combination of lifestyle and genetic factors increases your risk of developing it. These include:

  • family history – having a close family member (parent, sister, brother) with diabetes increases your risk 
  • age – the risk of getting diabetes rises as you get older, though it is becoming much more common in children, teenagers and young adults 
  • being overweight – having a lot of fatty tissue makes your cells resistant to insulin, which stops them using glucose from your blood. The glucose levels then increase, leading to diabetes 
  • not being active enough – doing physical activities takes glucose from your blood for energy and makes your cells more sensitive to insulin. It also helps you stay at a healthy weight. Inactivity increases your risk of diabetes
  • ethnic background – people from some ethnic groups (for example, people of African, Asian or Hispanic heritage) are more likely to get type 2 diabetes or to get it younger than others
  • having prediabetes, in which blood glucose levels are raised but are not high enough to be diagnosed as diabetes

Some other health conditions, such as high blood pressure, and some medications, for example, corticosteroids or thiazide diuretics, can also induce diabetes.

What are the effects of diabetes?

Aside from the symptoms that might suggest you have diabetes, the long-term effects of the condition can be extremely serious if blood glucose levels are not kept in check. Possible complications include:

  • Diseases of the heart and blood vessels, including angina, heart attack, stroke, narrowing of the arteries and high blood pressure.
  • Nerve damage, or neuropathy, which can cause tingling, numbness or pain in your limbs, especially the legs. It can eventually cause loss of all feeling in the affected limbs. Damage to nerves in your digestive system can make you feel or be sick, have diarrhoea or become constipated. 
  • Kidney damage, which can lead to kidney failure or irreversible kidney disease. This can leave people needing dialysis or a kidney transplant.
  • Eye conditions, such as diabetic retinopathy in which diabetes damages blood vessels in your retina and can lead to blindness. Your risk of cataracts and glaucoma also increase with diabetes.
  • Various foot problems caused by nerve damage or poor blood supply. Loss of feeling can become severe, and cuts, blisters and so forth can heal slowly and become seriously infected. Severe damage can mean you need toe, foot or leg amputation.
  • Skin problems, including fungal and bacterial infections.
  • Hearing problems are common in people with diabetes.
  • Problems with sex: nerve damage can cause erectile dysfunction in men, while women may have a loss of sex drive or sexual pleasure, vaginal dryness or discomfort or pain during sex.
  • Pregnancy complications, including miscarriage or stillbirth.

There’s evidence suggesting type 2 diabetes may increase your risk of developing Alzheimer’s disease. The exact link between the conditions isn’t fully understood but it appears that the less well blood sugar is controlled, the greater the risk.

How is diabetes treated?

The point of diabetes treatment is to control your blood glucose level to keep it as near normal as possible, while dealing with any symptoms you have. You may need medication to help you do this, but a great deal can be achieved through eating a healthier diet, losing weight if you need to and doing regular exercise. For some people, such lifestyle changes can be enough to keep blood glucose in a healthy range.


There’s no special ‘diabetic diet’ as such, though some foods will affect your blood glucose more than others and you may need to make some changes. You should aim for a healthy balanced diet that is low in fat, sugar and salt, and includes plenty of fruit and vegetables – at least five portions a day is recommended. Essentially you need a diet that would be good for just about anyone. 

“I’m more picky about where and what I eat, without trying to be fanatical about it”

– response in 2018 HealthUnlocked diabetes survey

You need carbohydrates, from starchy food like potatoes, bread, rice and pasta; protein, from meat, fish, eggs, beans, nuts and pulses; and, for calcium, dairy products such as skimmed or semi-skimmed milk, low-fat yoghurt and cheese. Use cooking oils with unsaturated fats, such as olive oil or sunflower oil.

Find out more about healthy eating with diabetes from:

Healthy weight

Being overweight is a big risk factor for diabetes and reducing weight to a healthy level can help get your blood glucose under control. In some cases, weight loss can get blood sugar back to normal levels. Most people are defined as overweight if they have a body mass index (BMI) of 25 or more; a BMI of 30 or more is obese – the thresholds are lower in some ethnic groups.

People generally gain weight because they consume more fuel (food) than they use up in activity. You can lose weight by adopting a healthy diet, reducing the calories you eat and increasing the amount of physical activity you do. For most overweight people, losing up to 10 percent of their weight over a year is realistic. 

There are various approaches to losing weight, including diets that are low in fat, low in calories or low in carbohydrates. Carbs have a big effect on blood glucose and are ranked from 0-100 in a system called the glycaemic index (GI) for how quickly they raise blood glucose – the lower the number, the more slowly they affect you. Some people opt for a low-GI diet but, while there’s evidence that it helps control of blood glucose, there’s less certainty about its weight-loss value for people with diabetes. Many low-GI foods are also high in fat, so you risk having an unbalanced diet.

There’s some evidence that the Mediterranean diet can work well for people with type 2 diabetes. It includes vegetables, beans, pulses, pasta, nuts, seeds and wholegrain bread, with some dairy products, eggs and fish.  

There are, of course, many commercial diets and group weight loss plans, some of which might be suitable. If you need to lose weight, your diabetes team will be able to give you advice. Whatever route you take, you need to be able to stick with it – small changes that are realistic for you will likely be more successful than trying to change everything about the way you eat in one go.

To lose weight effectively, you should combine changes in your diet with being more physically active.

“Dedicate yourself to keeping your sugar level under control. Look up the complications that diabetes can cause”

– response in 2018 HealthUnlocked diabetes survey


Guidelines for adults suggest that everyone over the course of a week should do at least 150 minutes of moderate-intensity aerobic activity, say, brisk walking or cycling, along with muscle-strengthening activities on two or more days a week. 

What exercise you can do will depend on your circumstances and any other health conditions you have. If you are unable to reach the guideline levels of activity, doing something is better than nothing. Almost any increase in physical activity will help your health and can pave the way for future improvements. 

Your doctor or diabetes care team will be able to advise you on suitable exercise.


When lifestyle changes aren’t enough to keep your blood glucose level under control, you will be offered medication in the form of pills. Some people will also need insulin injections.

Pills and tablets – There’s a wide range of pills available for diabetes that in one way or another reduce the amount of glucose in your blood. Because these medicines work in different ways, it’s common to have to take more than one to get a combined effect that works best for you. 

Insulin – If you need insulin, it must be injected. Insulin cannot be taken as a pill because your stomach would break it down like food and it wouldn’t reach your bloodstream. Different insulin preparations work in slightly different ways and last different lengths of time, from all day to a few hours or less. You may have to take more than one type. Most people on insulin treatment need two to four injections daily.

There are a couple of ways your insulin can be injected. It is usually by a syringe and needle or with an insulin pen – an auto-injector. Insulin can also be delivered continually with an insulin pump, a small device you wear attached to, say, a belt or waistband. These don’t suit everyone and there are advantages and disadvantages to each method.

Your healthcare team will explain how and when to inject your insulin. While many people are initially concerned about giving themselves injections, most get used to it quite quickly.

With all medication, and particularly insulin, you’ll need to monitor your condition closely to ensure your blood glucose is kept under control and that the medications and doses remain effective. You should discuss all medication you are prescribed with your doctor or diabetes team and be aware of any potential side effects.

Hypos – It’s possible on medication, especially insulin, to have what’s called a ‘hypo’ or episode of hypoglycaemia, where blood glucose levels become too low. Not everyone gets them, and the cause isn’t always clear, but they usually happen because the balance between medication, food and physical activity has been upset. 

A hypo can bring on a range of symptoms but typically makes you feel shaky, sweaty, weak, tired and hungry. Some people feel anxious, irritable or tearful and may notice palpitations, a quickened pulse, blurred vision or a headache. 

Hypos can usually be brought under control by eating or drinking something sugary that will quickly lift your blood glucose level, but in very severe cases you could lose consciousness and need medical treatment.

Living with diabetes

Diabetes is a lifelong condition that can affect many areas of your life. However, if it is well managed and you take care of yourself, it’s possible to delay or avoid many of the possible complications and continue to enjoy life to the full.

It’s worth learning as much as you can about your diabetes – the more you understand it, the better you’ll be able to manage it.

Keeping up a healthy lifestyle is crucial to controlling diabetes. You’ll also need regular – usually annual – checks on how well your diabetes is being controlled, on your eyes, feet, nerves, cholesterol, blood pressure, kidney function and weight.

Depending on your medications and whether you take insulin, you may need to monitor your blood glucose levels yourself day-to-day; your doctor or diabetes care team will advise you on this. Some people choose to do this even when they don’t strictly need to, whereas others find it a source of anxiety or a chore.

Smoking with diabetes increases your chance of complications – smoking itself is a risk factor for many of them – so stopping if you are a smoker should be one of your priorities.

Keeping well is important and it’s advisable to have the annual flu jab and the vaccination for pneumococcal pneumonia. Everyone gets ill from time to time and you’ll need to learn how to manage your diabetes when you aren’t well because of something else.

There are practical issues that will likely come up, such as rules around driving, travel plans, insurances, and financial assistance. Most people with diabetes can continue to drive, but there some circumstances that might prevent this. The American Diabetes Association has a tool to check the rules in any state and in the UK you can find out about diabetes and driving on GOV.UK.

Travel and holidays should not be a problem, but you will need to plan carefully, making sure you have enough medication and know where to get help if you need it. Insurances, including travel insurance, are sometimes problematic and, as with any long-term condition, there may be costs you hadn’t planned for.

There’s good information covering all these issues and more at the American Diabetes Association and at Diabetes UK.


Many people find they get great advice, support and information by talking to others with diabetes. There are numerous online groups, including Facebook groups, forums and communities, for people with diabetes.

There are also local support groups and events where you can meet people face-to-face. Your healthcare team may be able to recommend local groups near you.


There are many free and low-cost smartphone apps that can help you manage your diabetes. You can find them by searching for ‘diabetes’ in your device’s app store. To get an idea of the sorts of things they do, read Healthline’s reviews of the ‘Best diabetes apps of the year 2018’.

Main resources consulted in preparing this information

All resources were accessed during March 2018

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