What is the appropriate insulin dose for a 68-year-old male patient with type 2 diabetes, Hemoglobin A1c (HbA1c) level of 8.4%, and a weight of 66 kilograms?

Insulin Dosing for a 68-Year-Old Male with HbA1c 8.4% and Weight 66kg

For this patient, start with 10 units of basal insulin (such as insulin glargine/Lantus) once daily, administered at the same time each day, and titrate by 2-4 units every 3 days until fasting glucose reaches 80-130 mg/dL. 1

Initial Dose Calculation

For insulin-naive patients with type 2 diabetes and moderate hyperglycemia (HbA1c 8.4%), the recommended starting approach is:

• Start with 10 units once daily OR 0.1-0.2 units/kg body weight 1, 2
• For this 66 kg patient, weight-based dosing would be: 6.6-13.2 units daily
• The practical starting dose is 10 units once daily, which falls appropriately within this range and is the standard recommended starting point 1

Rationale for This Dosing Strategy

• HbA1c of 8.4% indicates moderate hyperglycemia that typically responds well to basal insulin initiation without requiring immediate basal-bolus therapy 1
• Patients with HbA1c <9% can usually start with basal-only insulin rather than more aggressive regimens 2, 1
• Higher starting doses (0.3-0.5 units/kg/day) are reserved for severe hyperglycemia (HbA1c ≥9%, blood glucose ≥300-350 mg/dL, or symptomatic/catabolic features), which this patient does not have 1, 3

Titration Protocol

Systematic uptitration is essential to achieve glycemic targets:

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

Foundation Therapy Requirements

• Continue metformin unless contraindicated (maximum effective dose 2000-2550 mg daily), as this combination provides superior glycemic control with reduced insulin requirements and less weight gain 1
• Consider continuing one additional non-insulin agent when starting basal insulin 1
• Discontinue sulfonylureas when advancing beyond basal-only insulin to prevent hypoglycemia 1

Critical Threshold: When to Add Prandial Insulin

Monitor for signs that basal insulin alone is insufficient:

• When basal insulin exceeds 0.5 units/kg/day (approximately 33 units for this patient) without achieving HbA1c goals, adding prandial insulin becomes more appropriate than continuing to escalate basal insulin alone 1
• If after 3-6 months of basal insulin optimization, fasting glucose reaches target but HbA1c remains above goal, add prandial insulin 1
• Start prandial insulin with 4 units of rapid-acting insulin before the largest meal, or use 10% of the basal dose 1

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1
• Reassess HbA1c every 3 months during active titration, then every 3-6 months once stable 1
• Assess adequacy of insulin dose at every clinical visit, looking for signs of overbasalization 1

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications, as this prolongs hyperglycemia exposure and increases complication risk 1
• Never discontinue metformin when starting insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain 1
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia, as this leads to overbasalization with increased hypoglycemia risk and suboptimal control 1

Patient Education Essentials

• Proper insulin injection technique and site rotation 1
• Recognition and treatment of hypoglycemia (treat glucose ≤70 mg/dL with 15 grams of fast-acting carbohydrate) 1
• Self-monitoring of blood glucose 1
• "Sick day" management rules 1
• Insulin storage and handling 1