Hyperosmolar syndrome

Overview

Hyperosmolar syndrome, more formally known as Hyperosmolar Hyperglycemic State (HHS), is a serious and potentially life-threatening complication of diabetes mellitus, most commonly seen in type 2 diabetes. It is characterized by extremely high blood glucose levels, severe dehydration, increased blood osmolality, and an absence of significant ketosis. HHS typically develops over days to weeks and often requires emergency medical intervention.

Causes

Hyperosmolar syndrome occurs when blood glucose levels rise dramatically and are not controlled, leading to osmotic diuresis and significant fluid loss. Contributing factors and triggers include:

• Poorly managed or undiagnosed type 2 diabetes

• Infection (e.g., pneumonia, urinary tract infection)

• Stroke or heart attack

• Certain medications (e.g., corticosteroids, diuretics, antipsychotics)

• Dehydration from vomiting, diarrhea, or inadequate fluid intake

• Acute illness or physical stress

Unlike diabetic ketoacidosis (DKA), HHS typically lacks significant ketosis because insulin levels, though low, are usually sufficient to prevent ketone formation.

Symptoms

Symptoms of hyperosmolar syndrome often develop gradually and may include:

• Extremely high blood glucose levels (often >600 mg/dL or 33.3 mmol/L)

• Excessive thirst and dry mouth

• Frequent urination followed by reduced urine output

• Profound dehydration (dry skin, sunken eyes, low blood pressure)

• Weakness or fatigue

• Confusion, lethargy, or altered mental status

• Seizures or coma in severe cases

Due to its insidious onset, patients may not realize the severity of their condition until it becomes critical.

Diagnosis

Diagnosis of hyperosmolar syndrome is based on clinical evaluation, laboratory testing, and ruling out other hyperglycemic emergencies like DKA. Diagnostic criteria typically include:

• Blood glucose >600 mg/dL (33.3 mmol/L)

• Serum osmolality >320 mOsm/kg

• Profound dehydration without significant ketones in blood or urine

• Arterial pH >7.3 (normal to slightly alkaline)

• Bicarbonate level >15 mEq/L

Additional tests may be conducted to identify underlying infections or contributing conditions.

Treatment

HHS requires prompt hospitalization and aggressive medical treatment to prevent complications or death. Treatment strategies include:

• Intravenous fluids: Rapid administration of isotonic saline to correct dehydration

• Insulin therapy: Low-dose IV insulin to gradually reduce blood glucose levels

• Electrolyte replacement: Especially potassium, as insulin therapy can cause shifts in potassium levels

• Treatment of underlying causes: Such as antibiotics for infections or stopping contributing medications

• Monitoring: Continuous monitoring of vital signs, glucose levels, electrolytes, and kidney function

Patients often require care in an intensive care unit (ICU) depending on the severity of symptoms.

Prognosis

The prognosis for hyperosmolar syndrome depends on the patient’s age, comorbidities, and how quickly treatment is initiated. With timely and appropriate management, many patients recover fully. However, the condition carries a higher mortality rate than diabetic ketoacidosis, especially in older adults or those with severe dehydration and delayed treatment. Long-term management of diabetes and patient education are essential to prevent recurrence.