In a pt with dka despite increase in dose of insulin blood glucose levels not decrease. Tests shows high glucagon and thyroxin. What could be the reason for increase glucose
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diabetic ketoacidosis AND hyperthyroidism
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hyperthyroidism increased hepatic glucose output insulin resistance glucagon diabetic ketoacidosis mechanism
The hyperglycemia is due to excess counter-regulatory hormones causing insulin resistance and increased hepatic glucose production.
- Glucagon directly raises blood glucose by stimulating hepatic glycogenolysis and gluconeogenesis. It also promotes lipolysis and ketone production, worsening DKA.
- High thyroxine, as in thyrotoxicosis, increases metabolic demand, intestinal glucose absorption, hepatic glucose turnover, and insulin requirement. It can therefore aggravate insulin resistance and make usual insulin doses appear ineffective.
So the likely explanation is DKA precipitated or worsened by thyrotoxicosis, with hyperglucagonemia, producing severe insulin-resistant hyperglycemia. The underlying cause of high thyroxine should be evaluated, especially thyroid storm/Graves disease in an acutely ill patient.
This is a high-risk situation: treat DKA using protocolized IV insulin, fluids, potassium monitoring, and address the thyrotoxicosis or other trigger concurrently.
Can it be because of glut 4 interlanization in muscle
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hyperthyroidism AND insulin resistance
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GLUT4 translocation insulin skeletal muscle intracellular vesicles hyperthyroidism insulin resistance glucose uptake
Not as the main explanation in this case.
Normally, insulin causes GLUT4 translocation from intracellular vesicles to the cell membrane in skeletal muscle and adipose tissue, allowing glucose uptake. If insulin signaling is resistant or impaired, less GLUT4 reaches the membrane, so peripheral glucose uptake falls. That can contribute to hyperglycemia.
But in this DKA scenario, the key mechanism suggested by high glucagon and thyroxine is mainly:
- Glucagon increases hepatic glucose output through glycogenolysis and gluconeogenesis.
- Thyroxine increases metabolic rate, hepatic glucose production, and insulin requirement, and can worsen insulin resistance.
- DKA itself involves profound insulin deficiency relative to counter-regulatory hormones, so insulin cannot adequately suppress liver glucose release or ketogenesis.
So you can say:
Reduced insulin-mediated GLUT4 translocation in muscle may contribute to peripheral insulin resistance and reduced glucose disposal, but the principal reason for persistent hyperglycemia here is increased liver glucose production driven by glucagon, amplified by thyrotoxicosis.
Also, the wording is important: it is not that GLUT4 is “internalized” as the causative event. In insulin deficiency/resistance, GLUT4 fails to translocate to the plasma membrane and remains in intracellular vesicles.
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