Hyperglycaemia

Hyperglycaemia, also known as high blood sugar, is a condition where there is an excessive amount of glucose circulating in the blood plasma. It is a significant indicator and complication of diabetes. Generally, blood sugar levels higher than 11.1 mmol/L (200 mg/dL) are considered hyperglycaemic, though symptoms might not manifest until levels reach 13.9–16.7 mmol/L (250–300 mg/dL). Chronic hyperglycaemia can lead to serious organ damage over time, especially if blood glucose levels consistently exceed 10–12 mmol/L (180–216 mg/dL).

Signs and Symptoms

Hyperglycaemia can present with varying degrees of severity and symptoms. Initially, it might be asymptomatic, but chronic elevated glucose levels can lead to diverse complications. Classic symptoms include frequent hunger (polyphagia), excessive thirst (polydipsia), and increased urination (polyuria). Additional symptoms might include blurred vision, fatigue, restlessness, weight changes, poor wound healing, dry mouth, dry or itchy skin, tingling in feet or heels, erectile dysfunction, recurrent infections, delayed gastric emptying, cardiac arrhythmia, stupor, coma, and seizures.

Complications

Untreated hyperglycaemia can lead to diabetic ketoacidosis, characterised by symptoms such as deep, rapid breathing (Kussmaul hyperventilation), confusion, dehydration, fruity-smelling breath, nausea, vomiting, abdominal pain, and impaired cognitive function. Chronic hyperglycaemia is strongly associated with heart attacks and death, even in patients without a history of heart disease or diabetes. It can cause nonketotic hyperosmolar syndrome and is linked to increased susceptibility to infections due to impaired immune function, particularly affecting neutrophil activity. Chronic inflammation and biochemical changes can further increase vulnerability to respiratory infections like tuberculosis, flu, and COVID-19.

Causes

Hyperglycaemia is most commonly caused by diabetes mellitus due to low insulin levels or insulin resistance. Other endocrine disorders, sepsis, infections, intracranial diseases, convulsions, terminal diseases, prolonged surgeries, stress, and excessive carbohydrate intake can also cause hyperglycaemia.

Endocrine Disorders

Various hormones such as cortisol, catecholamines, growth hormone, glucagon, and thyroid hormones can increase blood glucose levels when present in excess, leading to conditions like Cushing's syndrome, pheochromocytoma, acromegaly, hyperglucagonaemia, and hyperthyroidism.

Insulin Resistance

Obesity contributes significantly to insulin resistance, making it difficult to manage blood glucose levels. Insulin resistance prevents glucose from being converted into glycogen, thus elevating blood sugar levels.

Medications

Certain medications, including corticosteroids, beta blockers, thiazide diuretics, and antipsychotics, can increase the risk of hyperglycaemia.

Stress

Stress-induced hyperglycaemia can occur due to stroke, myocardial infarction, or other acute stressors, increasing mortality risk. Hormonal changes and increased proinflammatory cytokines can interrupt carbohydrate metabolism, leading to excessive glucose production.

Diagnosis

Monitoring blood glucose levels is very important. Levels are measured in either millimoles per litre (mmol/L) or milligrammes per deciliter (mg/dL). Normal fasting levels are about 4 to 6 mmol/L (80 to 110 mg/dL). Chronic hyperglycaemia can be measured via the HbA1c test, whereas acute hyperglycaemia can range from 8 to 15 mmol/L (144 to 270 mg/dL).

Treatment

Treatment involves addressing the underlying cause, such as diabetes, through lifestyle modifications, diet, and medication. Acute hyperglycaemia is often treated with insulin, while chronic cases may require oral hypoglycaemic therapy and lifestyle changes. Increasing aerobic exercise and adopting diets high in unsaturated fats and whole wheat carbohydrates, such as the Mediterranean diet, can help control blood glucose levels. Medications like sulphonylureas, metformin, and dipeptidyl peptidase-4 inhibitors may also be prescribed.

Epidemiology

Hyperglycaemia is more prevalent in low to middle-income groups due to limited access to education and healthy food. Physical inactivity and high-calorie consumption contribute to the increasing incidence of hyperglycaemia, with non-whites showing higher susceptibility.

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Self-assessment MCQs (single best answer)

What is hyperglycaemia?

What are the classic symptoms of hyperglycaemia?

Which serious condition can untreated hyperglycaemia lead to?

Which hormone is NOT associated with increasing blood glucose levels?

Which of the following is a common cause of hyperglycaemia?

What measurement indicates chronic hyperglycaemia?

Which lifestyle modification can help manage hyperglycaemia?

Which medication is NOT typically used to treat hyperglycaemia?

What dietary change can help reduce hyperglycaemia?

Which group is more susceptible to hyperglycaemia?