What is the appropriate method to calculate the basal insulin dose for a 70-kilogram patient with type 2 diabetes?

Calculating Basal Insulin Dose

For a 70-kilogram patient with type 2 diabetes, start with 10 units of basal insulin once daily OR calculate 0.1-0.2 units/kg/day (7-14 units), administered at the same time each day. 1

Standard Initial Dosing Algorithm

For Mild-to-Moderate Hyperglycemia (A1C <9%)

• Start with 10 units once daily as the simplest approach 1
• Alternative weight-based calculation: 0.1-0.2 units/kg/day 1
  • For a 70 kg patient: 7-14 units once daily 1
• Continue metformin unless contraindicated 1

For Severe Hyperglycemia (A1C ≥9% or glucose ≥300-350 mg/dL)

• Use higher starting doses: 0.3-0.5 units/kg/day as total daily insulin 1, 2
  • For a 70 kg patient: 21-35 units total daily dose 1, 2
• Implement basal-bolus therapy immediately if A1C ≥10-12% with symptomatic/catabolic features 1, 2
  • Split 50% as basal insulin, 50% as prandial insulin divided among meals 1, 2

Titration Protocol

Standard Adjustment Schedule

• 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 glucose: 80-130 mg/dL 1
• If hypoglycemia occurs: reduce dose by 10-20% immediately 1

Critical Threshold Recognition

When basal insulin exceeds 0.5 units/kg/day (35 units for a 70 kg patient), stop escalating basal insulin alone and add prandial insulin instead. 1, 2 Continuing beyond this threshold leads to "overbasalization" with increased hypoglycemia risk without improved control. 1, 2

Clinical signals of overbasalization include: 1, 2

• Basal dose >0.5 units/kg/day
• Bedtime-to-morning glucose differential ≥50 mg/dL
• Episodes of hypoglycemia
• High glucose variability throughout the day

Special Population Adjustments

High-Risk Patients (Elderly >65 years, Renal Failure, Poor Oral Intake)

• Start with lower doses: 0.1-0.25 units/kg/day 1, 2
• For a 70 kg patient: 7-17.5 units once daily 1, 2

Hospitalized Patients

• Insulin-naive or low-dose home insulin: 0.3-0.5 units/kg/day total, with half as basal 1, 2
  • For a 70 kg patient: 10.5-17.5 units basal insulin 1, 2
• High-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% upon admission 1, 2

Type 1 Diabetes

• Total daily insulin: 0.4-1.0 units/kg/day, typically 0.5 units/kg/day for metabolically stable patients 1, 2
  • For a 70 kg patient: 35 units total daily dose 1, 2
• Basal component: 40-60% of total daily dose (approximately 50%) 1, 2
  • For a 70 kg patient: 17.5 units basal insulin 1, 2

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications—this prolongs hyperglycemia exposure and increases complication risk 1, 2
• Never discontinue metformin when starting insulin unless contraindicated—the combination provides superior control with less weight gain 1, 2
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this causes overbasalization 1, 2
• Never use sliding scale insulin as monotherapy—it treats hyperglycemia reactively rather than preventing it 1, 2

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1
• Reassess every 3 days during active titration to adjust dose 1, 2
• Reassess every 3-6 months once stable to evaluate overall glycemic control and A1C 1, 2
• Consider adding prandial insulin if A1C remains above target after 3-6 months despite achieving fasting glucose goals 1, 2