Hyperglycemic hyperosmolar state (HHS)

Introduction

Hyperglycemic hyperosmolar state (HHS) is an acute complication of diabetes as DKA. HHS is primarily seen in individuals with type 2 DM.

Clinical Features

The prototypical patient with HHS is an elderly individual with type 2 DM, with a several week history of polyuria, weight loss, and diminished oral intake that culminates in mental confusion, lethargy, or coma.

The physical examination reflects profound dehydration and hyperosmolality and reveals hypotension, tachycardia, and altered mental status.

Notably absent are symptoms of nausea, vomiting, and abdominal pain and the Kussmaul respirations characteristic of DKA. HHS is often precipitated by a serious, concurrent illness such as myocardial infarction or stroke. Sepsis, pneumonia, and other serious infections are frequent precipitants and should be sought.

Pathophysiology

Relative insulin deficiency and inadequate fluid intake are the underlying causes of HHS. Insulin deficiency increases hepatic glucose production (through glycogenolysis and gluconeogenesis) and impairs glucose utilization in skeletal muscle (see above discussion of DKA). Hyperglycemia induces an osmotic diuresis that leads to intravascular volume depletion, which is exacerbated by inadequate fluid replacement. The absence of ketosis in HHS is not completely understood.

Laboratory Abnormalities and Diagnosis

The laboratory features in HHS are summarized as follows;


Glucose 33.3–66.6 (mmol/L (600-1200 mg/dL)
Sodium 135–145 meq/L
Potassium Normal
Magnesium Normal
Chloride Normal
Phosphate Normal
Creatinine Moderately high
Osmolality 330–380 mOsm/mL
Plasma ketones +/-
Serum bicarbonate Normal to slightly low
Arterial pH >7.3
Arterial PCO Normal
Anion gap [Na-(Cl+HCO3)] Normal to slightly higher

Treatment

Volume depletion and hyperglycemia are prominent features of both HHS and DKA. In both disorders, careful monitoring of the patient’s fluid status, laboratory values, and insulin infusion rate is crucial. Underlying or precipitating problems should be aggressively sought and treated. In HHS, fluid losses and dehydration are usually more pronounced than in DKA due to the longer duration of the illness. The patient with HHS is usually older, more likely to have mental status changes, and more likely to have a life-threatening precipitating event with accompanying comorbidities. Even with proper treatment, HHS has a substantially higher mortality than DKA (up to 15% in some clinical series).