Can hypoglycemia (low blood sugar) cause hyperkalemia (elevated potassium levels)?

Hypoglycemia Does Not Cause Hyperkalemia—The Opposite Is True

A blood sugar of 58 mg/dL (hypoglycemia) does not cause a potassium of 6.9 mEq/L (hyperkalemia). In fact, the relationship works in the opposite direction: hyperglycemia (high blood sugar) can cause hyperkalemia, particularly in patients with renal impairment or diabetes. 1, 2

The Actual Mechanism: Hyperglycemia Causes Hyperkalemia

In diabetic ketoacidosis and hyperglycemic crises, patients commonly present with hyperkalemia despite total body potassium depletion. 1 The mechanism involves:

• Severe hyperglycemia creates hyperosmolality in the extracellular fluid, which drives potassium passively out of cells into the bloodstream 2
• Insulin deficiency (which accompanies hyperglycemia in diabetic states) prevents potassium from entering cells, further elevating serum levels 1, 2
• This combination is particularly dangerous in patients with impaired renal function who cannot excrete the excess potassium 2

Two fatal cases documented patients with severe hyperglycemia (1,152 and 1,185 mg/dL) who developed extreme hyperkalemia (7.9 and 9.3 mEq/L) and died from cardiac arrest, demonstrating this relationship clearly. 2

Why Hypoglycemia Cannot Cause Hyperkalemia

Hypoglycemia has no physiologic mechanism to cause hyperkalemia. In fact, the treatment of hyperkalemia with insulin (which lowers blood sugar) demonstrates the inverse relationship:

• Insulin therapy promotes the shift of potassium from extracellular to intracellular space, effectively lowering serum potassium levels 1
• When treating hyperkalemia with insulin plus glucose, the primary concern is subsequent hypoglycemia (occurring in 6-9% of cases), not hyperkalemia 3, 4
• Hypoglycemia following insulin administration for hyperkalemia requires monitoring for 4-6 hours, but the potassium remains lowered 5

Clinical Implications for Your Patient

If your patient has both hypoglycemia (58 mg/dL) and hyperkalemia (6.9 mEq/L), these are two separate problems requiring independent evaluation and treatment:

Immediate Assessment Priorities

• Check for severe hyperglycemia history or recent insulin administration that could explain both findings 1, 3
• Assess renal function immediately, as kidney disease is a common cause of hyperkalemia 6, 2
• Obtain an ECG to evaluate for hyperkalemic cardiac changes (peaked T waves, widened QRS, loss of P waves) 7, 6
• Review medications: ACE inhibitors, ARBs, potassium-sparing diuretics, and NSAIDs all cause hyperkalemia 8, 6

Treatment Approach

For the hyperkalemia (6.9 mEq/L):

• Administer IV calcium gluconate immediately if ECG changes are present 7, 6
• Use insulin (5-10 units) with dextrose (50g) to shift potassium intracellularly, but monitor closely given the existing hypoglycemia 5, 4
• Consider albuterol nebulizer as an adjunct therapy 6, 5

For the hypoglycemia (58 mg/dL):

• Treat with 15-20g of rapidly absorbed carbohydrate immediately 7
• Recheck blood glucose within 15 minutes and retreat if still <70 mg/dL 7
• If using insulin for hyperkalemia treatment, increase dextrose to 50g and monitor glucose hourly for 4-6 hours 5, 4

Common Pitfall to Avoid

Do not assume these two abnormalities are causally related. The coexistence of hypoglycemia and hyperkalemia suggests either:

• Recent insulin administration (which lowered both glucose and potassium, with potassium now rebounding) 3, 4
• Two independent pathologic processes requiring separate investigation 6
• Severe renal impairment with poor glucose homeostasis 2

Never delay treatment of either condition while investigating the other—both require urgent intervention. 7, 6