I will explain about insulin and hypokalemia.

Why insulin causes hypokalemia

People with diabetes under insulin therapy tend to be hypokalemic.

The reason is that insulin has a function to incorporate potassium into the cell from outside the cell.

This is called potassium shift (K shift).

K shift

A part of K in the extracellular fluid is actively transferred into the cell via the electrokinetic Na pump.

Insulin stimulates Na pump activity of skeletal muscle and hepatocytes irrespective of glucose and promotes uptake of K into cells.

Symptoms and Risk of Hypokalemia

The reference range of serum potassium level is 3.6 to 4.8 mEq / L.

If the serum potassium level is 3.5 mEq / L or less, skeletal muscle symptoms such as muscle weakness and tetany appear.

Also, gastrointestinal symptoms such as vomiting, constipation and paralytic ileus appear.

In addition, abnormal glucose metabolism, renal hypertrophy, polyuria appear.

Furthermore, electrocardiogram abnormalities such as T wave flattening, U wave appearance, PQ interval extension etc. appear.

In the study of patients with acute myocardial infarction, the mortality rate is low when the serum potassium is in the range of “3.5 to 4.0 mEq / L”, and it is reported that outside the range, the mortality rate, ventricular fibrillation incidence and cardiac arrest are high.

Treatment of hypokalemia

Treating hypokalemia, oral supplementation of potassium (vegetables, fruits, juice etc.) is the primary choice.

If insufficient, the second choice is replenishing with oral medication or infusioning of potassium preparation.

During potassium supplementation, regularly check of the serum potassium level is needed.

In case of infusion, the potassium preparation should be diluted to 40 mmol / L or less and administered at a rate not exceeding 20 mmol / h.

In case of type 2 diabetes mellitus, glucose promotes insulin secretion and causes potassium to inflow into the cell, which may exacerbate hypokalemia.

Therefore, a glucose-free solution such as physiological saline or extracellular fluid replenisher is desirable as a potassium lysate.

Reduce the amount of insulin

Incidentally, as a countermeasure other than supplementing potassium, there is a way to reduce the dose of insulin.

However, decreasing the amount of insulin may lead to an increase in blood glucose levels or an increase in serum potassium levels.

Therefore, when decreasing the amount of insulin, it is necessary to pay attention to the movement of blood glucose level and blood glucose level potassium value.

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