Epidemiology

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Etiology

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Pathophysiology

DKA

Intracellular potassium deficit

• As a result of hyperglycemic hyperosmolality, potassium shifts along with water from inside cells to the extracellular space and is lost in the urine.
• Insulin normally promotes cellular potassium uptake but is absent in DKA, compounding the problem.
• A total body potassium deficit develops in the body, although serum potassium may be normal or even paradoxically elevated.
• Insulin deficiency → hyperosmolality → K⁺ shift out of cells + lack of insulin to promote K⁺ uptake → intracellular K⁺ depleted → total body K⁺ deficit despite normal or even elevated serum K⁺

Tip

There is a total body potassium deficit in DKA. This becomes important during treatment, when insulin replacement leads to rapid potassium uptake by depleted cells and patients may require potassium replacement.

HHS

• Primarily affects patients with type 2 diabetes
• The pathophysiology of HHS is similar to that of DKA.
• However, in HHS, there are still small amounts of insulin being secreted by the pancreas, and this is sufficient to prevent DKA by suppressing lipolysis and, in turn, ketogenesis.
• HHS is characterized by symptoms of marked dehydration (and loss of electrolytes) due to the predominating hyperglycemia and osmotic diuresis.

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Clinical features

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Diagnostics

Tip

• DKA is the diagnosis in patients with type 1 diabetes who have hyperglycemia, ketonuria, and high anion gap metabolic acidosis with decreased bicarbonate!
• HHS is the diagnosis in patients with type 2 diabetes who have hyperglycemia and hyperosmolality!

Electrolytes and renal function

• Sodium:
  • Hyponatremia is common in both DKA and HHS, due to hypovolemic hyponatremia and hypertonic hyponatremia
    • Uncontrolled high blood sugar (hyperglycemia) in DKA acts like a magnet for water.
    • This extra sugar in the blood pulls water out of cells, causing them to shrink.
    • While the total body water stays the same, the concentration of sodium in the remaining extracellular fluid (outside the cells) gets diluted.
  • Always check corrected sodium for hyperglycemia.
• Potassium in DKA: normal or elevated (despite a total body deficit)

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Treatment

• Fluid resuscitation: initially with isotonic saline (0.9% NaCl)
• Potassium repletion: for potassium level < 5.3 mEq/L
• Insulin therapy: initiate short-acting insulin once potassium level is > 3.3 mEq/L
• Identify and treat precipitating causes (e.g., sepsis).

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