What are the common symptoms of hyperglycemia?

Common Symptoms of Hyperglycemia

The most common symptoms of hyperglycemia are increased thirst (polydipsia), frequent urination (polyuria), and blurry vision, which typically occur when blood glucose levels exceed the renal threshold of approximately 180 mg/dL. 1

Primary Symptoms

Hyperglycemia presents with several characteristic symptoms that should be recognized promptly:

• Increased thirst (polydipsia) - One of the earliest and most noticeable symptoms
• Frequent urination (polyuria) - Often accompanies increased thirst
• Blurry vision - Visual changes due to glucose-induced changes in the lens
• Fatigue or weakness - General feeling of tiredness or lack of energy
• Dry mouth - Related to dehydration from increased urination
• "Not feeling right" - General malaise or feeling unwell
• Sweet or funny taste in the mouth - Can be a subtle indicator of elevated blood glucose

Progression to Diabetic Ketoacidosis (DKA)

If hyperglycemia is left untreated, especially in type 1 diabetes, it can progress to diabetic ketoacidosis (DKA), which presents with:

• Nausea and vomiting - Often an early sign of developing DKA
• Abdominal pain - Can be severe and mimic other abdominal emergencies
• Fruity odor on breath - Due to ketone production
• High levels of ketones in blood and urine - Measurable with appropriate testing
• Dehydration - Worsens as the condition progresses
• Rapid breathing - Respiratory compensation for metabolic acidosis
• Confusion - Mental status changes as the condition worsens
• Loss of consciousness - In severe cases 2, 1

It's important to note that patients using insulin pumps may experience DKA more rapidly due to lack of insulin supply if the pump malfunctions 2.

Symptom Categories

Research has identified four distinct groupings of hyperglycemic symptoms 3:

1. Agitation symptoms:

   • Feeling tense
   • Irritability
   • Restlessness
   • Poor concentration

2. Osmotic symptoms (most specific to hyperglycemia):

   • Thirst
   • Dry mouth
   • Need to urinate
   • Not feeling right
   • Sweet/funny taste
   • Weakness

3. Neurological symptoms:

   • Dizziness
   • Blurred vision
   • Light-headedness
   • Weakness

4. Malaise symptoms:

   • Headache
   • Nausea

Risk Factors and Causes

Hyperglycemia can be triggered by several factors:

• Insufficient insulin or oral medication
• Excessive food intake
• Inadequate physical activity
• Stress or illness (including infections)
• Certain medications (especially corticosteroids)
• Changes in insulin requirements due to physiological factors 2, 4

Clinical Implications

Early recognition of hyperglycemic symptoms is crucial for prompt intervention to prevent progression to more severe metabolic derangements and reduce the risk of long-term complications 1. Chronic hyperglycemia can lead to both acute complications (osmotic diuresis, dehydration, electrolyte imbalances) and long-term damage (retinopathy, nephropathy, neuropathy, cardiovascular disease).

Symptom intensity tends to be greater in younger patients, and the blood glucose threshold for symptom onset (median 15 mmol/L or 270 mg/dL) may be lower in people with normal awareness of hypoglycemia 3.