5.2 Identify the causes of hyperglycaemia

This guide will help you answer 5.2 Identify the causes of hyperglycaemia.

Hyperglycaemia refers to an abnormally high level of glucose in the blood. Glucose is a type of sugar our bodies use for energy, and its levels are controlled mainly by the hormone insulin. People with diabetes are most at risk, but it can affect anyone under certain circumstances.

Blood glucose levels are measured in millimoles per litre (mmol/L). Hyperglycaemia is usually diagnosed when levels go above 7 mmol/L before a meal or 11 mmol/L two hours after eating. High glucose levels over a long period can cause serious health problems. This makes it important to know what leads to hyperglycaemia so it can be managed or prevented.

Medical Conditions That Cause Hyperglycaemia

Some health conditions disrupt the body’s ability to manage glucose. Diabetes is the most common medical reason for hyperglycaemia.

• Type 1 diabetes: The pancreas makes little or no insulin. This means glucose stays in the blood instead of moving into cells. Type 1 diabetes often starts in childhood or young adulthood. Without enough insulin, blood sugar rises quickly, leading to hyperglycaemia.
• Type 2 diabetes: The body either does not respond to insulin properly (insulin resistance) or does not make enough insulin. This type is more common in adults but is now seen in younger people too. It usually develops gradually.
• Gestational diabetes: This occurs during pregnancy. Hormone changes make the body less sensitive to insulin, causing increased blood glucose. It often improves after the baby is born, but both mother and child have a higher risk of later developing type 2 diabetes.
• Pancreatitis: Inflammation of the pancreas can reduce insulin output, leading to hyperglycaemia.
• Hormonal disorders: Conditions that affect other hormones can impact glucose control. For example:
• Cushing’s syndrome causes high levels of cortisol, which raises blood sugar.
• Acromegaly involves too much growth hormone, also raising glucose levels.
• Hyperthyroidism can stimulate the liver to produce excess glucose.

Lifestyle Factors

How a person lives day-to-day affects blood sugar levels. Workers supporting people in health and social care settings see many lifestyle causes of hyperglycaemia.

Diet

Eating patterns have a direct impact on blood sugar.

• High intake of sugary foods and drinks: Consuming lots of cakes, sweets, soft drinks or desserts increases glucose in the blood much faster than the body can deal with it.
• Eating large portions: Overeating increases the glucose load which may overwhelm insulin.
• Frequent snacking: Eating often, especially snacks high in sugar or carbohydrates, keeps blood sugar constantly high.

Lack of Physical Activity

Activity helps the body use up glucose for energy.

• Sedentary lifestyle: Little or no exercise means less glucose is taken up by muscles.
• Bed rest or reduced mobility: People who are unwell and stay in bed may become hyperglycaemic if their insulin or medication doses are not adjusted.

Stress

Both emotional and physical stress have a big impact on blood glucose.

• Emotional stress: Feelings such as worry, anger or grief trigger the release of hormones like cortisol and adrenaline. These hormones make the liver release more glucose into the blood.
• Physical stress: Illness, surgery, pain or infections can all increase stress hormones. This often causes blood sugar to rise, sometimes very quickly.

Medication-Related Causes

Some medicines can raise blood sugar as a side effect. Health and social care workers should be aware of the following drugs:

• Steroids (corticosteroids): These drugs are used for asthma, arthritis and some skin conditions. They raise blood sugar by blocking the action of insulin and making the liver release more glucose.
• Diuretics: “Water tablets” used for blood pressure or heart issues can affect how the body handles glucose.
• Anti-psychotics: Certain medicines for mental health problems can make the body less sensitive to insulin.
• Some cancer treatments: These may impact the way the pancreas works or interfere with insulin.

Drug interactions can also lead to hyperglycaemia. For example, if a patient’s insulin dose is wrongly reduced or missed when another drug is started, their blood sugar may rise.

Missed Medication Doses

For people with diabetes, keeping up with insulin or other blood sugar lowering medicines is key.

• Missed insulin injections: Missing a dose or taking less than needed means less glucose moves into the cells. It stays in the blood instead, causing hyperglycaemia.
• Incorrect medication timing: Insulin should be taken at set times related to meals. If taken late or at the wrong time, blood sugar may rise.
• Problems using insulin pumps or pens: If there are issues with devices, such as empty cartridges or technical faults, glucose may not be well controlled.

For those taking oral diabetes medicines:

• Forgetting tablets: Skipping a dose sometimes leads to higher blood sugar, especially if food intake remains the same.

Infection and Illness

Being unwell is a common cause of raised glucose in people with and without diabetes.

• Bacterial or viral infections: Illness triggers stress hormones that block the effect of insulin and cause the liver to release more glucose.
• Fever or high temperature: The body’s energy needs change, and blood sugar control is often thrown off.
• Serious injury or trauma: These events lead to big surges in stress hormones, raising glucose.

People may find it harder to keep to their usual diet and medication routine when unwell. This makes blood sugar harder to manage.

Hormonal Changes

Hormones are substances that control different functions in the body, including growth, energy use, and stress response.

• Puberty: Teenagers produce extra growth hormone, which can make controlling blood sugar more difficult for those with diabetes.
• Menstruation: Some women notice higher blood sugar just before their period because of hormonal changes.
• Pregnancy: Hormone shifts in pregnancy can reduce insulin action, leading to higher glucose.
• Menopause: Hormone levels change again, affecting how the body uses insulin.

Other Contributing Factors

Certain less common situations can cause or contribute to hyperglycaemia.

• Pain: Ongoing or severe pain increases stress hormones, raising blood sugar.
• Dehydration: Low body fluids can lead to more concentrated blood glucose.
• Overeating when feeling unwell: Some people eat more to ‘feel better’ when sick, but this may raise blood sugar, especially if medication is not adjusted.
• Alcohol: Drinking alcohol can cause swings in blood sugar. Sometimes the body releases stored glucose in response, especially if binge drinking.
• Lack of sleep: Poor sleep disrupts hormones involved in glucose regulation.

Individual Risk Factors

Every person is different. Some have a greater risk based on their own makeup and life situation.

• Age: Older adults may have slower insulin response.
• Family history: Diabetes and its early forms often run in families.
• Ethnicity: Some groups (such as people of South Asian, African or Caribbean descent) have a higher risk of developing insulin problems.

The Body’s Response to Hyperglycaemia

When blood sugar rises, the body tries to lower it. The kidneys remove extra glucose by making more urine. This can lead to dehydration and further raise blood sugar. If hyperglycaemia continues unchecked, it can lead to dangerous conditions such as diabetic ketoacidosis in people with type 1 diabetes. This is a medical emergency.

Monitoring and Early Warning Signs

Spotting high blood sugar early is important.

Common signs include:

• Thirst
• Frequent urination
• Tiredness and low energy
• Blurred vision
• Headache

If someone starts showing these symptoms, checking their blood sugar is the safest step.

Who Is Most at Risk?

Some people must be watched more closely.

• People diagnosed with diabetes
• Older adults or those with multiple health conditions
• People taking steroids or other glucose-raising drugs
• Pregnant women or women with polycystic ovary syndrome
• People with limited mobility or frailty

Staff in health and social care roles should understand which residents or clients may develop hyperglycaemia so they can spot early signs and act.

Preventing Hyperglycaemia

Although the focus is on causes, small steps can lower the chance of high blood sugar.

• Supporting people to take medication at the correct times
• Promoting healthy eating – less sugar, controlled portions, regular mealtimes
• Encouraging gentle exercise, such as walking
• Stress management or emotional support when needed
• Monitoring blood glucose for those at risk

Care plans must account for any factors that make hyperglycaemia more likely.

Final Thoughts

Understanding the causes of hyperglycaemia helps you protect and support people in care. There is no single cause. Medical conditions, missed medications, emotional or physical stress, lifestyle choices and even everyday changes in routine can all trigger high blood sugar.

Your support makes a difference. By being observant, you can spot early warning signs and help people stick to treatment and healthy routines. You are often the first to notice if something seems wrong, and your actions can prevent more serious complications. Keep learning about what puts people at risk, listen to their concerns, and work together to manage day-to-day factors. Remember, good care isn’t only about giving medication; it’s about seeing the whole person and knowing how to reduce problems before they start.