Hyperglycemic hyperosmolar coma

Second most common form of hyperglycemic coma.

Can be a life-threatening emergency.

Less common than diabetic ketoacidosis, and differs in the magnitude of dehydration, ketosis, and acidosis.

Has a higher mortality rate than diabetic ketoacidosis, estimated to be approximately 15%.

In as many as one third of cases, the clinical features overlap with diabetic ketoacidosis.

Diagnostic features include: Plasma glucose level of 600 mg/dL or greater, serum osmolality of 320 mOsm/kg or greater, dehydration up to an average of 9L, serum pH greater than 7.30, bicarbonate concentration greater than 15 mEq/L, small ketonuria and absent-to-low ketonemia, alteration in consciousness.

Coma is found in fewer than 20% of patients with HHS.

Most commonly occurs in patients with type 2 diabetes mellitus who have some concomitant illness.

Underlying mechanism is a reduction in the effective circulating insulin with a concomitant elevation of counter-regulatory hormones, such as glucagon, catecholamines, cortisol, and growth hormone.

Decreased renal clearance and decreased peripheral utilization of glucose lead to hyperglycemia.

Hyperglycemia and hyperosmolarity result in an osmotic diuresis and an osmotic shift of fluid to the intravascular space, resulting intracellular dehydration.

Diuresis leads to loss of electrolytes, such as sodium and potassium.

Incidence is less than 1 case per 1000 person-years.

The mortality rate is 10-20%

Mortality usually due to a comorbid illness, and increases with age and increasing severity of hyperosmolality.

African Americans, Hispanics, and Native Americans are disproportionately affected.

Prevalence is slightly higher in females.

Mean age of onset early in the seventh decade of life, in contrast, the mean age for diabetic ketoacidosis is early in the fourth decade.

Elderly and demented are at the highest risk.

In 30-40% of cases it is the initial presentation of diabetes.

Develops over a course of days to weeks

Several days of increasing dehydration is usually preent.

Patients may present with polydipsia, polyuria, weight loss, and weakness.

Neurologic changes may be present and include drowsiness, lethargy, delirium, coma, seizures, visual changes, sensory changes and hemiparesis.

Examine the patient for evidence of hyperosmolar hyperglycemic state (HHS), focusing on hydration status, mentation, and signs of possible underlying causes, such as a source of infection.

Clinical findings for dehydration are present.

Formerly called hyperglycemic, hyperosmolar, non-ketotic coma.

Characterized by hyperglycemia in the absence of significant ketosis, hyperosmolality and dehydration.

Occurs in patients with mild or occult diabetes.

Most patients middle aged or elderly.

When serum osmolality exceeds 310 mosm/kg lethargy and confusion occur, while coma can ensue if osmlality exceeds 320-330 mosm/kg.

Patients frequently have chronic kidney disease or congestive heart failure.

Often precipitated by infection, stroke, myocardial infarction or surgery.

May be associated with phenytoin, corticosteroids, diazoxide, diuretics and peritoneal dialysis.

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