⚠️ Hyperosmolar Hyperglycemic State (HHS): The Silent Emergency

While most people with diabetes worry about low blood sugar, an extremely high blood sugar that goes untreated for days can lead to a different kind of emergency — Hyperosmolar Hyperglycemic State (HHS). This condition occurs almost exclusively in Type 2 diabetes and is characterised by severe dehydration and very high blood glucose, often exceeding 600 mg/dL. It develops more slowly than diabetic ketoacidosis (DKA), but it can be just as deadly if not recognised and treated promptly. Dr. Ravi Sishir Reddy explains what HHS is, who is at risk, the warning signs, and what to do.

1. What Is Hyperosmolar Hyperglycemic State?

HHS is a condition where the blood sugar becomes extremely elevated, causing massive fluid loss through the urine. The body tries to eliminate the excess glucose by increasing urine output (osmotic diuresis), leading to profound dehydration. Unlike DKA, there is usually enough insulin present in the body to prevent significant fat breakdown, so ketones are minimal or absent. However, the dehydration can become so severe that it causes the blood to become concentrated (hyperosmolar), leading to confusion, coma, and in the worst cases, death.

The typical blood sugar in HHS is above 600 mg/dL, often reaching 800‑1,000 mg/dL or more. The serum osmolality (a measure of concentration) is markedly elevated, which pulls water out of brain cells and causes neurological symptoms.

2. How Is HHS Different from DKA?

Feature	HHS	DKA
Typical diabetes type	Type 2	Type 1 (can occur in Type 2)
Speed of onset	Days to weeks	Hours to a day
Blood sugar	Often >600 mg/dL	Usually >250 mg/dL
Ketones	Minimal or absent	Present (moderate to large)
Dehydration	Very severe	Moderate to severe
Acidosis (blood pH)	Absent (pH normal)	Present (pH <7.3)
Mortality rate	5‑15%	<1% (with treatment)

3. Warning Signs and Symptoms of HHS

HHS often develops insidiously over several days to weeks. The early signs are easy to overlook or attribute to other causes. As it worsens, the symptoms become more dramatic:

• Excessive thirst and dry mouth that does not improve with drinking.
• Frequent urination with large volumes.
• Progressive weakness and fatigue.
• Blurred vision and dizziness.
• Nausea, though vomiting is less common than in DKA.
• Confusion, disorientation, slurred speech — the brain cells shrink due to the high serum osmolality.
• In severe cases: seizures, hallucinations, coma.
• Very dry, warm skin — the skin does not sweat.

If an elderly person with Type 2 diabetes becomes confused and dehydrated, HHS must be considered immediately.

4. What Triggers HHS?

HHS is usually triggered by an underlying stressor that raises blood sugar and impairs fluid intake, especially in older adults with Type 2 diabetes. Common triggers include:

• Infection (pneumonia, urinary tract infection, sepsis) — the most common trigger.
• Undiagnosed or untreated Type 2 diabetes (HHS can be the first presentation).
• Poor medication adherence — missing doses of insulin or oral medications for days.
• Major illness or surgery — stress hormones drive blood sugar up.
• Dehydration — from vomiting, diarrhoea, diuretics, or simply not drinking enough water, especially in the elderly with a diminished thirst sensation.
• High‑sugar beverages — consuming large amounts of sweetened drinks (fruit juice, soda) during illness can worsen hyperglycemia and osmotic diuresis.
• Certain medications — corticosteroids, thiazide diuretics, and atypical antipsychotics can increase blood sugar.

5. What to Do If You Suspect HHS

HHS is a medical emergency requiring hospitalisation. Treatment involves gradual rehydration with intravenous fluids, correction of electrolyte imbalances (especially potassium and sodium), and controlled insulin administration to bring down the blood sugar slowly. Rapid correction can cause cerebral edema (brain swelling) or sudden shifts in electrolytes that can be fatal.

If you or a loved one with diabetes shows these signs — especially confusion or altered consciousness with very high blood sugar — call an ambulance or go to the emergency room immediately.

6. How to Prevent HHS

• Stay hydrated: Drink adequate water throughout the day, especially during illness or hot weather. Older adults should be encouraged to drink even if not thirsty.
• Monitor blood sugar regularly: During an infection or any illness, check glucose more frequently — at least every 4‑6 hours.
• Have a sick‑day plan: Discuss with your doctor what to do when you are sick — what to eat, how to adjust medications, and when to call for help.
• Never stop your medication without medical advice, even if you are not eating well. Basal insulin is still needed.
• Recognise the early signs: Excessive thirst, frequent urination, fatigue, and mental fogginess should prompt checking blood sugar and contacting a doctor.
• Educate caregivers: Family members who look after elderly individuals with diabetes should know the signs of HHS and ensure they have access to a glucometer.