What is the initial approach to insulin therapy for patients requiring it?

Initial Approach to Insulin Therapy

For patients requiring insulin therapy, start with basal insulin alone at 10 units once daily or 0.1-0.2 units/kg/day, administered at the same time each day, unless the patient presents with marked hyperglycemia (blood glucose ≥300-350 mg/dL or HbA1c ≥10-12%) with symptoms, in which case basal-bolus insulin should be initiated immediately. 1, 2

Starting Basal Insulin: The Standard Approach

Initial Dosing Strategy

• Begin with basal insulin monotherapy using either intermediate-acting NPH or long-acting analogs (glargine or detemir) 1
• Standard starting dose: 10 units once daily OR 0.1-0.2 units/kg body weight per day 1, 2
• Continue metformin unless contraindicated, and possibly one additional non-insulin agent 1
• Long-acting analogs (glargine, detemir) are associated with modestly less overnight hypoglycemia and possibly slightly less weight gain (detemir) compared to NPH, though they are more expensive 1

Dose Titration Algorithm

Increase basal insulin systematically based on fasting glucose levels: 1, 2

• If fasting glucose 140-179 mg/dL: increase by 2 units every 3 days 1, 2
• If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days 1, 2
• Target fasting plasma glucose: 80-130 mg/dL 1, 2
• If hypoglycemia occurs without clear cause, reduce dose by 10-20% immediately 1, 2

Critical Threshold: When to Stop Escalating Basal Insulin

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin rather than continuing to escalate basal insulin alone. 1, 2 This prevents "overbasalization," which manifests as: 1, 2

• Bedtime-to-morning glucose differential ≥50 mg/dL 1, 2
• Hypoglycemia episodes 1, 2
• High glucose variability 1, 2
• Basal dose >0.5 units/kg/day 1, 2

Exception: Severe Hyperglycemia Requires Immediate Basal-Bolus Therapy

When to Start with Basal-Bolus Insulin from the Outset

Initiate basal-bolus insulin immediately (not basal alone) in patients with: 1, 2

• Blood glucose ≥300-350 mg/dL 1
• HbA1c ≥10-12% with symptomatic or catabolic features 1
• Ketonuria (mandatory insulin initiation) 1

For these patients, use higher starting doses of 0.3-0.5 units/kg/day as total daily dose, split between basal and prandial insulin. 1, 2

Adding Prandial Insulin: When Basal Alone Is Insufficient

Indications for Advancing Beyond Basal-Only Therapy

Add prandial insulin when: 1

• After 3-6 months of basal insulin optimization, fasting glucose reaches target (80-130 mg/dL) but HbA1c remains above goal 1
• Basal insulin dose approaches 0.5-1.0 units/kg/day without achieving glycemic targets 1
• Significant postprandial glucose excursions persist despite controlled fasting glucose 1

Prandial Insulin Initiation Protocol

• Start with 4 units of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal OR 10% of current basal dose 1, 2
• Rapid-acting analogs provide better postprandial glucose control than regular insulin and should be dosed just before the meal 1
• Titrate by 1-2 units or 10-15% every 3 days based on postprandial glucose readings 1, 2

Essential Patient Education Components

Comprehensive education is imperative and must include: 1

• Self-monitoring of blood glucose technique 1
• Proper insulin injection technique and site rotation 1
• Insulin storage and handling 1
• Recognition and treatment of hypoglycemia 1
• "Sick day" management rules 1

Instruction in self-titration of insulin doses based on glucose monitoring improves glycemic control. 1 Where available, certified diabetes educators are invaluable in guiding patients through this process. 1

Common Pitfalls to Avoid

• Do not delay insulin initiation in patients not achieving glycemic goals with oral medications 1, 2
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to suboptimal control and increased hypoglycemia risk 1, 2
• Do not discontinue metformin when adding or intensifying insulin therapy unless contraindicated 1, 2
• Do not use insulin as a threat or describe it as personal failure—emphasize the progressive nature of type 2 diabetes and the utility of insulin to maintain control 1
• Daily fasting blood glucose monitoring is essential during titration—failure to monitor adequately delays achievement of glycemic targets 1, 2