What is the initial dosing strategy for starting basal bolus insulin therapy?

How to Start Basal-Bolus Insulin Therapy

Initial Dosing Strategy

For insulin-naive patients with type 2 diabetes requiring basal-bolus therapy, start with a total daily dose of 0.3-0.5 units/kg/day, split 50% as basal insulin (given once daily) and 50% as rapid-acting prandial insulin (divided among three meals). 1

Calculating the Starting Dose

• Calculate total daily dose based on body weight: 0.3-0.5 units/kg/day for patients with severe hyperglycemia (HbA1c ≥9%, blood glucose ≥300-350 mg/dL, or symptomatic/catabolic features) 2, 1
• Divide the total daily dose: 50% as basal insulin (glargine, detemir, or degludec) given once daily at the same time each day 2, 1
• Divide the remaining 50% as rapid-acting prandial insulin (lispro, aspart, or glulisine) split among three meals 2, 1
• For a 70 kg patient: Total daily dose = 0.4 units/kg × 70 kg = 28 units total; give 14 units basal insulin once daily + approximately 5 units before each meal (breakfast, lunch, dinner) 1

Risk-Based Dose Adjustments

• For high-risk patients (age >65 years, renal failure, or poor oral intake), use lower starting doses of 0.1-0.25 units/kg/day to prevent hypoglycemia 2, 1
• For hospitalized patients previously on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% upon admission 2

Basal Insulin Component

• Administer basal insulin (glargine, detemir, or degludec) subcutaneously once daily at the same time each day into the abdominal area, thigh, or deltoid 3
• Do not dilute or mix basal insulin with any other insulin or solution 3
• Rotate injection sites to reduce risk of lipodystrophy and localized cutaneous amyloidosis 3
• The basal insulin component restrains hepatic glucose production and controls fasting and between-meal glucose levels 4, 2

Prandial Insulin Component

• Give rapid-acting insulin analogs (lispro, aspart, or glulisine) immediately before meals (0-15 minutes) 2
• Distribute prandial insulin evenly among three meals initially, then adjust based on carbohydrate content and glucose patterns 1
• Prandial insulin addresses postprandial glucose excursions that basal insulin cannot control 2

Titration Protocol

Basal Insulin Titration

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

Prandial Insulin Titration

• Adjust each prandial dose independently based on the glucose reading 2 hours after that specific meal 2
• Increase prandial insulin by 1-2 units or 10-15% every 3 days based on postprandial glucose readings 2
• If pre-lunch glucose is high, increase breakfast prandial dose; if pre-dinner glucose is high, increase lunch prandial dose; if bedtime glucose is high, increase dinner prandial dose 2

Foundation Therapy

• Continue metformin unless contraindicated, as it reduces total insulin requirements and provides complementary glucose-lowering effects 2, 1
• Discontinue sulfonylureas when starting basal-bolus therapy to prevent hypoglycemia 2
• Consider adding a GLP-1 receptor agonist to minimize weight gain and hypoglycemia risk 2

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during the titration phase 2, 1
• Monitor pre-meal and 2-hour postprandial glucose readings to guide prandial insulin adjustments 2
• Assess insulin adequacy at every clinical visit, looking for signs of overbasalization (bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, high glucose variability) 2, 1
• Check HbA1c every 3 months during intensive titration 2

Stepwise Intensification Alternative

For patients with less severe hyperglycemia (HbA1c <9%), consider starting with basal insulin alone and adding prandial insulin stepwise rather than starting full basal-bolus immediately. 2, 1

• Start with 10 units of basal insulin once daily or 0.1-0.2 units/kg/day 2
• Titrate basal insulin by 2-4 units every 3 days until fasting glucose reaches 80-130 mg/dL 2
• When basal insulin exceeds 0.5 units/kg/day or fasting glucose is controlled but HbA1c remains elevated after 3-6 months, add prandial insulin 2
• Start with 4 units of rapid-acting insulin before the largest meal or 10% of the basal dose 2, 1
• Add prandial insulin to additional meals sequentially (one meal, then two meals, then three meals) based on glucose patterns 1

Patient Education Essentials

• Teach proper insulin injection technique and site rotation 2
• Educate on recognition and treatment of hypoglycemia: treat blood glucose ≤70 mg/dL with 15 grams of fast-acting carbohydrate 2
• Provide self-monitoring of blood glucose training with prescribed monitoring schedule 2
• Explain "sick day" management rules and insulin storage requirements 2
• Instruct patients to check insulin labels before injection to prevent accidental mix-ups between insulin products 3

Common Pitfalls to Avoid

• Do not delay insulin initiation in patients not achieving glycemic goals, as this prolongs exposure to hyperglycemia and increases complication risk 2
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without adequate prandial coverage, as this causes overbasalization with increased hypoglycemia and suboptimal control 2, 1
• Do not abruptly discontinue all oral medications when starting insulin—continue metformin unless contraindicated 2
• Do not use premixed insulins in hospital settings due to unacceptably high rates of iatrogenic hypoglycemia 2
• Do not blame missed carbohydrate coverage for fasting hyperglycemia—fasting glucose reflects basal insulin adequacy, not meal coverage 2
• Never share insulin pens, syringes, or needles between patients, even if the needle is changed 3

Special Clinical Situations

Transitioning from IV to Subcutaneous Insulin

• Calculate total subcutaneous dose as half of the IV insulin infused over 24 hours 2
• Give 50% as basal insulin once in the evening and divide the remaining 50% by 3 for rapid-acting insulin before each meal 2

Patients on Corticosteroids

• Increase prandial and correction insulin by 40-60% or more in addition to basal insulin 2
• For patients without diabetes on steroids, consider a single morning dose of NPH; for patients with diabetes on steroids, add 0.1-0.3 units/kg/day glargine to the usual insulin regimen 2

Type 1 Diabetes

• Total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day, with 0.5 units/kg/day being typical for metabolically stable patients 2
• Divide approximately 40-50% as basal insulin and 50-60% as prandial insulin 2
• Higher doses are required during puberty, pregnancy, and medical illness, potentially exceeding 1.0 units/kg/day 2