Immediate Insulin Dosing for Severe Hyperglycemia in an Adolescent
This 16-year-old male with severe symptomatic hyperglycemia (blood glucose 384 mg/dL) requires immediate insulin therapy with an initial total daily dose of approximately 20-33 units, split as basal-bolus regimen, given his weight of 289 pounds (131 kg) and symptomatic presentation with dizziness and lightheadedness. 1
Initial Assessment and Treatment Decision
This patient presents with marked hyperglycemia (≥250 mg/dL) with symptoms (dizziness, lightheadedness), which mandates immediate insulin initiation per American Diabetes Association guidelines for youth with diabetes 2. The symptomatic presentation with polyuria-equivalent symptoms (dizziness and lightheadedness can indicate dehydration from osmotic diuresis) requires urgent treatment 2.
Critical first step: Before administering insulin, immediately check for diabetic ketoacidosis (DKA) by obtaining venous blood gases, serum electrolytes, blood urea nitrogen, creatinine, and urine ketones 1. This is non-negotiable given the severe hyperglycemia.
Specific Insulin Dosing Protocol
If NO Ketoacidosis Present (Outpatient Management):
Initial total daily insulin dose: 0.3-0.5 units/kg/day 1
For this 131 kg patient:
- Conservative approach: 0.15 units/kg = 20 units total daily dose (accounting for insulin sensitivity in newly diagnosed patients)
- Standard approach: 0.3 units/kg = 39 units total daily dose
- Recommended starting point: 25-30 units total daily dose
Distribution:
- 50% as basal insulin (long-acting: glargine, detemir, or degludec): 12-15 units once daily 1, 2
- 50% as prandial insulin (rapid-acting: lispro, aspart, or glulisine): divided before meals, approximately 4-5 units before each of 3 meals 1, 2
If Ketoacidosis IS Present (Requires Hospitalization):
Continuous IV insulin infusion at 0.1 units/kg/hour 1
- For this patient: 13.1 units/hour initially
- Target glucose decline: 50-75 mg/dL per hour until glucose reaches 200-250 mg/dL 1
- Concurrent fluid resuscitation with isotonic saline is mandatory 1
Practical Implementation
Immediate Office Management:
Give rapid-acting insulin subcutaneously NOW: 8-10 units as initial correction dose (approximately 1 unit per 40-50 mg/dL above target of 140 mg/dL) 2, 3
Recheck blood glucose in 2 hours to assess response 2
If no ketoacidosis: Prescribe basal-bolus regimen as outlined above and arrange close follow-up within 24-48 hours 1
If ketoacidosis present: Transfer immediately to emergency department for IV insulin therapy 2
Critical Monitoring Requirements
- Blood glucose monitoring at least 4 times daily during titration phase: fasting and before each meal 1
- Daily fasting blood glucose checks are essential 1
- Recheck HbA1c in 3 months to assess treatment effectiveness 1
Common Pitfalls to Avoid
Never use sliding scale insulin alone without basal coverage - this approach has inferior outcomes and increases complication risk 1. The American College of Clinical Endocrinologists explicitly states that correction insulin should not be used alone without basal insulin 1.
Do not delay insulin initiation - the American Diabetes Association guidelines are clear that youth with marked hyperglycemia (≥250 mg/dL) who are symptomatic should be treated initially with basal insulin while metformin is initiated and titrated 2.
Avoid overly aggressive initial dosing - while this patient has severe hyperglycemia, starting with 0.15-0.3 units/kg is safer than higher doses to prevent hypoglycemia during the adjustment period 1.
Patient Education Priorities
Teach the patient to never stop insulin during illness, even when not eating, to prevent DKA 1. This is a critical safety point that must be emphasized at the initial visit.
Hydration is essential - instruct the patient to maintain hydration with non-caloric fluids, particularly given current symptoms suggesting dehydration 1.
Hypoglycemia recognition must be taught immediately, as insulin therapy carries this risk 1.
Follow-Up Insulin Adjustment
If glycemic targets are not met with initial basal insulin dosing, move to multiple daily injections with basal and premeal bolus insulins rather than simply increasing basal insulin doses 2. The goal is physiologic insulin replacement, not just correction of hyperglycemia with a single insulin type.