What is the recommended insulin dosing for a 49-year-old, 80 kg male patient with new-onset diabetes, severe hyperglycemia (glucose level of 628), and not in diabetic ketoacidosis (DKA)?

Insulin Dosing for Severe Hyperglycemia Without DKA

For this 49-year-old, 80 kg male with glucose 628 mg/dL and no DKA, initiate basal-bolus insulin immediately with a total daily dose of 24-40 units (0.3-0.5 units/kg/day), giving 50% as basal insulin once daily and 50% as prandial insulin divided among three meals. 1, 2

Immediate Assessment Required

Before initiating insulin, confirm the absence of DKA by checking venous blood gases, serum electrolytes, blood urea nitrogen, creatinine, and urine ketones 1. This patient's glucose of 628 mg/dL places him in the severe hyperglycemia category requiring aggressive intervention, but the absence of DKA allows outpatient management with subcutaneous insulin rather than IV insulin infusion 1.

Specific Insulin Dosing Algorithm

Initial Total Daily Dose Calculation

• Start with 0.3-0.5 units/kg/day as total daily insulin dose for this level of severe hyperglycemia 1, 2
• For an 80 kg patient: 24-40 units total daily dose
• The higher end (0.5 units/kg = 40 units) is appropriate given the glucose level of 628 mg/dL 1

Basal-Bolus Distribution

Basal insulin (long-acting):

• Give 50% of total daily dose as basal insulin once daily 1, 2
• For 40 units total: 20 units of insulin glargine (Lantus) or detemir once daily 1, 2
• Administer at the same time each day, typically at bedtime 2

Prandial insulin (rapid-acting):

• Give 50% of total daily dose as prandial insulin, divided among three meals 1, 2
• For 40 units total: Approximately 7 units of rapid-acting insulin (lispro, aspart, or glulisine) before each meal 1
• Administer 0-15 minutes before eating 2

Why Basal-Bolus Rather Than Basal-Only

At glucose 628 mg/dL, basal insulin alone is insufficient. 3, 1 This patient requires both fasting glucose control (basal insulin) and postprandial glucose control (prandial insulin) from the outset 1. Starting with basal-only therapy would unnecessarily prolong hyperglycemia exposure and delay achievement of glycemic targets 1, 2.

Youth with marked hyperglycemia (blood glucose ≥250 mg/dL) without acidosis should be treated initially with basal insulin while metformin is initiated, but this adult patient at 628 mg/dL requires more aggressive basal-bolus coverage 3.

Titration Protocol

Basal Insulin Adjustment

• Increase basal insulin by 4 units every 3 days if fasting glucose remains ≥180 mg/dL 1, 2
• Increase by 2 units every 3 days if fasting glucose is 140-179 mg/dL 1, 2
• Target fasting glucose: 80-130 mg/dL 1, 2
• If hypoglycemia occurs, reduce dose by 10-20% immediately 1, 2

Prandial Insulin Adjustment

• Increase prandial insulin by 1-2 units every 3 days based on 2-hour postprandial glucose readings 1, 2
• Target postprandial glucose <180 mg/dL 3
• Adjust each meal's dose independently based on the glucose reading 2 hours after that specific meal 1

Essential Concurrent Therapy

Metformin must be initiated simultaneously unless contraindicated by renal dysfunction (this patient has normal creatinine of 0.35) 1. Start metformin 500-850 mg once or twice daily with meals, titrating up to 2000 mg daily over 1-2 weeks as tolerated 1. Metformin reduces insulin requirements, provides complementary glucose-lowering effects, and minimizes weight gain associated with insulin therapy 1, 2.

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during the titration phase 1, 2
• Check pre-meal and 2-hour postprandial glucose at least 4 times daily initially 1
• Recheck HbA1c in 3 months to assess treatment effectiveness 1
• Monitor for hypoglycemia symptoms, especially during the first few weeks 1

Critical Threshold to Recognize

If basal insulin eventually exceeds 0.5 units/kg/day (40 units for this patient) without achieving glycemic targets, intensify prandial insulin rather than continuing to escalate basal insulin alone. 1, 2 This prevents "overbasalization," which causes hypoglycemia and suboptimal control 1, 2. Clinical signals of overbasalization include bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia episodes, and high glucose variability 1, 2.

Common Pitfalls to Avoid

• Never use sliding scale insulin as monotherapy for new-onset diabetes—this approach is explicitly condemned by all major guidelines and leads to dangerous glucose fluctuations 1, 2
• Do not delay insulin initiation in favor of oral agents alone when glucose is this elevated—prolonged hyperglycemia increases complication risk 1, 2
• Do not start with basal insulin alone at this glucose level—the patient needs both basal and prandial coverage from day one 1
• Do not discontinue metformin when starting insulin unless contraindicated—this leads to higher insulin requirements and more weight gain 1, 2

Patient Education Priorities

• Proper insulin injection technique and site rotation 1
• Recognition and treatment of hypoglycemia with 15 grams of fast-acting carbohydrate 1
• Self-monitoring of blood glucose technique 1
• "Sick day" management rules: never stop insulin during illness, even when not eating 1
• Insulin storage and handling 1

Expected Outcomes

With this basal-bolus regimen at appropriate weight-based dosing, expect glucose levels to decline by 50-75 mg/dL per day initially, with achievement of fasting glucose <200 mg/dL within 3-5 days and target range (80-130 mg/dL) within 1-2 weeks 1. HbA1c reduction of 2-3% is achievable over 3 months with proper insulin intensification 2.