Diabetes is a chronic disease and does not have a cure, except for the case of gestational diabetes which usually disappears after childbirth. Treatments have improved a great deal in recent years and research continues to discover preventive strategies and new treatments.

Hypoglycaemia occurs when your blood glucose level falls below 70 mg/dL. All patients treated with insulin or some oral antidiabetic drugs, can experience an episode of hypoglycaemia.

The most common symptoms are:

Person with sweats, tremors and paleness

Tremors, sweating, paleness, palpitations, feeling hungry, dizziness (known as adrenergic symptoms).

Blurred person, representing blurred vision

Altered speech, blurred vision, lack of coordination (called neuroglycopenic symptoms).

Glucometer measuring blood glucose levels

Some people do not notice any changes when they have blood sugar levels below 70 mg/dL. This is known as undetected hypoglycaemia. Patients who experience episodes of undetected hypoglycaemia must maximise preventive measures more than ever to ensure their safety.

Hypoglycaemia is caused by:

A plate of chicken, cutlery and a clock: mealtimes

Not eating or eating a meal later than usual.

Person running and an upward arrow indicating an increase in exercise.

Doing more exercise than usual.

Insulin injection and an upward arrow indicating a dose increase

Injecting more insulin than usual in relation to your carbohydrate intake.

A pitcher of beer and a Martini or cocktail glass

Drinking a significant amount of alcohol can also provoke the onset of hypoglycaemia.

In case of hypoglycaemia, you must eat or drink ONE of the following options:

Soft drink or sugary beverage

1 glass (200 mL) of fruit juice, or

A glass with water into which a medicine in an sachet is poured.

1 glass of milk and 1 sachet of sugar, or

Two sachets of sugar, one opened and one closed

2 sachets of sugar, or

Drink can with a straw

1 glass or ½ can of a soft drink (that is not sugar-free or light).

Hyperglycaemia is an excessively high amount of sugar in the blood. All diabetes patients, regardless of whether their treatment is with insulin, tablets or through diet and exercise, can suffer episodes of hyperglycaemia.

Some people do not notice any difference. While others may be thirsty, need to urinate more and, occasionally, may even lose weight despite feeling hungrier and eating more. The best way of finding out if your sugar level is high is to measure your capillary blood glucose level.

Hyperglycaemia is caused by:

Drink can with a straw

Eating foods with a high sugar content: soft drinks, bakery products, cakes, ice-creams, chocolate.

Fruit, flour and a bottle of milk with an arrow to indicate increase

Eating more fruit, grains and milk products than usual.

Exercising person with a down arrow indicating fatigue

Exercising less than usual.

A hand holding an insulin injection with a question mark on it

Forgetting to inject insulin.


Infections: a cold, a boil, etc., especially if the patient has a fever. An infection can be a cause of hyperglycaemia even when all the other signs are correct.

An infectious process may rapidly result in an uncontrolled metabolism. Hormone and sugar levels tend to increase during infections and so patients must take the following into account:

Injection, insulin monitoring and a watch

Even if you eat fewer carbohydrates, you will probably still need to take rapid-acting insulin to correct high sugar levels.

Person drinking a standing glass of water

Hydrate yourself correctly, particularly if you have gastroenteritis, to prevent dehydration.

Two glucometers with two clocks on top, representing the control of sugar levels

Increase the frequency of capillary blood glucose and ketones in urine or blood tests, if necessary.

Medicines, pills

Treat the infection causing the hyperglycaemia.

In case of hyperglycaemia

Person drinking a standing glass of water

Drink more water than usual, even if you are not thirsty, to prevent dehydration.

Two glucometers with two clocks on top, representing the control of sugar levels

Carry out more capillary blood sugar tests and check your ketones in urine level.

Insulin injection and an upward arrow indicating a dose increase

Never stop taking your insulin injections at the agreed times. You may need to increase the dose if the hyperglycaemia lasts for more than two hours.

Fresh baked bread

If you are not hungry, you may stop eating salads and/or vegetables, meat, fish, etc., but you must always ensure the same amount of grains, fruit and milk products, and adapt their preparation, e.g., eating grains in soups, semolina, or drinking fruit juices.

Diabetic ketoacidosis is an acute imbalance typically associated with type 1 diabetes, and also, but much less frequently, with type 2 diabetes. It is characterised by excessively high ketone levels in the blood. These high blood ketone levels are due to an insulin deficit or increased insulin requirements (e.g., because of an infection) which means the body cannot use glucose as an energy source and must use fats instead. This phenomenon results in an excess of ketone bodies in the blood (by-products released when fats are used as an energy source). The presence of ketone bodies in the blood can reduce blood pH; this may evolve into a life-threatening situation that requires hospitalisation.

Person vomiting in a toilet

What will I notice? Excessive ketone levels sustained throughout the day may cause gastric distress, nausea, vomiting and even breathing difficulties. You may notice that your breath tastes of apple.

Phone call

What should I do? Contact your healthcare team as soon as possible. 

Hyperosmolar syndrome is an acute imbalance that occurs in patients with type 2 diabetes. It is characterised by extremely high blood sugar levels, but without the presence of ketones.

Person with the urge to urinate next to the toilet

Hyperosmolar syndrome can produce symptoms such as: excessive thirst and/or need to urinate, weakness, nausea, weight loss, dry mouth and tongue, convulsions, confusion and coma.


Phone call

What should I do? Contact your healthcare team as soon as possible. If you do not act, then there is a risk you could fall into a diabetic coma.

The majority of chronic complications are usually the result of a vascular problem. Vascular problems occur when large blood vessels become blocked (obstructed) or when smaller vessels are damaged, as in the case of the arteries in the eye’s retina and those found in the kidneys.

In the long-term, diabetes can affect: the eyes (diabetic retinopathy), the kidneys (chronic kidney failure), the heart (cardiopathie) or the feet (diabetic foot).

Chronic complications have diminished in recent years due to improved treatments that have provided the opportunity to obtain greater control over hyperglycaemia and other risk factors.

Glucometer measuring blood glucose levels

Maintain good control over your diabetes.

A blood vessel with cholesterol in its walls that restricts blood flow

Prevent or reduce cardiovascular risk factors. Cardiovascular risk is the risk of developing a heart (angina pectoris or infarction) or brain condition (stroke) during a given period of time, generally the next 5 to 10 years. The habits or behaviours that increase this risk, which are what we call cardiovascular risk factors, are: cholesterol, high blood pressure, being overweight and obesity, smoking tobacco, diabetes and stress.


Once patients have adapted to the treatment, and depending on each case and situation, check-ups with the healthcare team are usually held every 3 or 6 months. Some studies have provided conclusive evidence that good metabolic control prevents or delays the onset of future complications associated with diabetes and therefore improves the quality of life.

Substantiated information by:

Daría Roca Espino
Enrique Esmatjes Mompo
Irene Vinagre Torres
Margarida Jansà Morató
Mercè Vidal Flor

Published: 20 February 2018
Updated: 24 November 2021

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.


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