What does a blood glucose level of 42.1 mmol/L indicate and how should it be managed with insulin?

Management of Severe Hyperglycemia (42.1 mmol/L)

A blood glucose level of 42.1 mmol/L represents a severe hyperglycemic emergency requiring immediate insulin therapy, preferably with intravenous insulin infusion in a monitored setting, along with aggressive fluid resuscitation and electrolyte management.

Initial Assessment

• Evaluate for symptoms of hyperglycemic crisis including polyuria, polydipsia, nausea, vomiting, abdominal pain, altered mental status, and signs of dehydration 1
• Check for ketones in urine or blood to rule out diabetic ketoacidosis (DKA), especially in patients with type 1 diabetes 1
• Assess vital signs, hydration status, and mental status to determine severity of the emergency 1

Immediate Management

• For critically ill patients or those with hyperglycemic crisis, initiate continuous intravenous insulin infusion using a validated protocol 2, 1
• Start IV fluid resuscitation with normal saline to correct dehydration 1
• Monitor electrolytes closely, especially potassium, as insulin therapy will cause potassium to shift intracellularly 3
• Target glucose range of 140-180 mg/dL (7.8-10.0 mmol/L) for most hospitalized patients 2

Insulin Therapy Protocol

• For IV insulin therapy, use ultra-rapid insulin diluted to concentration of 1 IU/mL 2
• Include simultaneous glucose infusion (100-150 g/day) once blood glucose falls below 14 mmol/L to prevent hypoglycemia 2
• Measure blood glucose every hour until stable, then every 2 hours 2
• Adapt insulin infusion flow rate based on glycemic response 2

Transition to Subcutaneous Insulin

• Once the patient is stable and blood glucose levels are consistently below 14 mmol/L, transition to subcutaneous insulin 1
• Start subcutaneous insulin 1-2 hours before discontinuing IV insulin to prevent rebound hyperglycemia 1
• Use a basal-bolus regimen rather than sliding scale insulin alone 1, 3
• HUMALOG (insulin lispro) should be given within 15 minutes before meals or immediately after meals when using subcutaneous administration 3

Monitoring and Adjustments

• Glucose monitoring is essential for patients receiving insulin therapy 3
• Changes to insulin regimen should be made cautiously and only under medical supervision 3
• Adjust insulin doses daily based on blood glucose patterns 1
• Monitor for hypoglycemia, which is the most common adverse effect of insulin therapy 3

Common Pitfalls to Avoid

• Using sliding scale insulin alone without basal insulin is ineffective and strongly discouraged 1
• Delaying insulin therapy for severe hyperglycemia increases risk of complications 1
• Inadequate monitoring of blood glucose can lead to both persistent hyperglycemia and hypoglycemic events 1
• Be aware that insulin causes a shift in potassium from extracellular to intracellular space, potentially leading to hypokalemia 3

Special Considerations

• For patients with renal or hepatic impairment, frequent glucose monitoring and insulin dose reduction may be required 3
• Malfunction of insulin pumps or infusion sets can rapidly lead to hyperglycemia and ketosis 3
• Control of glucose levels rather than absolute levels of exogenous insulin appear to account for mortality benefit 4
• A blood glucose threshold of approximately 144-200 mg/dL (8.0-11.1 mmol/L) has been associated with mortality benefit in critically ill patients 4