What are the symptoms of hyperglycemia?

Symptoms of Hyperglycemia

The most common symptoms of hyperglycemia include thirst (polydipsia), frequent urination (polyuria), blurred vision, and weight loss, which may be accompanied by polyphagia (increased hunger). 1

Classic Symptoms of Hyperglycemia

Primary Symptoms

• Polydipsia (excessive thirst) - One of the earliest and most common symptoms
• Polyuria (frequent urination) - Results from osmotic diuresis when blood glucose exceeds the renal threshold
• Blurred vision - Due to glucose-induced changes in lens shape and fluid balance
• Weight loss - Particularly in type 1 diabetes or severe hyperglycemia

Additional Symptoms

• Fatigue or weakness
• Dry mouth
• Sweet or funny taste in the mouth
• "Not feeling right" 2

Age-Related Differences in Presentation

Adults

Adults typically experience the classic symptoms of polyuria, polydipsia, and weight loss when hyperglycemic 1.

Elderly Patients

Elderly patients may present differently:

• Less likely to experience typical symptoms of polyuria and polydipsia
• Renal threshold for glycosuria increases with age
• Thirst mechanisms are often impaired
• May present with weight loss and fatigue that can be mistakenly attributed to aging or "failure to thrive"
• Confusion may be a presenting symptom 1

Children and Adolescents

Children may show the classic symptoms but might also present with:

• Lethargy
• Behavioral changes
• Poor school performance 1

Severe Hyperglycemia and Complications

If hyperglycemia remains untreated over days, it can progress to more serious conditions:

Diabetic Ketoacidosis (DKA)

Characterized by:

• Nausea and vomiting
• High levels of ketones in blood and urine
• Abdominal pain
• Fruity-smelling breath
• Can be life-threatening if not treated promptly 1

Hyperosmolar Hyperglycemic State (HHS)

Characterized by:

• Profound dehydration
• Neurological symptoms ranging from lethargy to coma
• Marked elevation of blood glucose without significant ketosis
• More common in older adults with type 2 diabetes 3

Symptom Groupings

Research has identified four main symptom groupings in hyperglycemia 2:

1. Agitation symptoms:

   • Feeling tense
   • Irritability
   • Restlessness
   • Poor concentration

2. Osmotic symptoms (most specific to hyperglycemia):

   • Thirst
   • Dry mouth
   • Frequent urination
   • Not feeling right
   • Sweet/funny taste
   • Weakness

3. Neurological symptoms:

   • Dizziness
   • Blurred vision
   • Light-headedness
   • Weakness

4. Malaise symptoms:

   • Headache
   • Nausea

Clinical Implications

• Symptom intensity tends to be greater in younger patients 2
• The median blood glucose threshold for symptom onset is approximately 15 mmol/L (270 mg/dL), but this can range from 8-30 mmol/L (144-540 mg/dL) 2
• Patients using insulin infusion pumps may develop DKA more rapidly if insulin supply is interrupted 1
• Hyperglycemia in hospitalized patients is associated with increased risk of infections and complications 4, 5

Important Considerations

• Symptoms may be absent or subtle in the early stages of hyperglycemia
• Osmotic symptoms (thirst, polyuria) are most specific for hyperglycemia
• Symptoms may be mistaken for other conditions, especially in elderly patients
• Regular blood glucose monitoring is essential for early detection of hyperglycemia, especially in those with known diabetes

Understanding these symptoms is crucial for early recognition and prompt treatment of hyperglycemia to prevent progression to more serious complications.