What is the recommended dose of insulin glargine for a patient with type 2 diabetes and impaired renal function?

Insulin Glargine Dosing in Type 2 Diabetes with Impaired Renal Function

Initial Dose Recommendation

For a patient with type 2 diabetes and impaired renal function, start insulin glargine at a reduced dose of 0.1 units/kg/day (or approximately 5-8 units once daily), which is lower than the standard 0.1-0.2 units/kg/day used in patients with normal renal function. 1, 2

Rationale for Dose Reduction in Renal Impairment

• Approximately one-third of insulin degradation occurs in the kidneys, and impaired kidney function prolongs insulin half-life, substantially increasing hypoglycemia risk 1
• Patients with significant creatinine elevations have a 5-fold increase in severe hypoglycemia frequency 1
• The combination of decreased insulin clearance and impaired renal gluconeogenesis creates compounding risk for dangerous hypoglycemic episodes 1

Standard Dosing for Patients WITHOUT Renal Impairment

• The American Diabetes Association recommends starting insulin glargine at 10 units once daily or 0.1-0.2 units/kg body weight for insulin-naive patients with type 2 diabetes 3, 4, 2
• For patients with severe hyperglycemia (A1C ≥9%, blood glucose ≥300-350 mg/dL), consider higher starting doses of 0.3-0.5 units/kg/day as total daily dose, split between basal and prandial insulin 3, 4

Specific Dosing Algorithm for Renal Impairment

• Reduce the standard insulin dose by 15-25% immediately in patients with moderate-to-severe CKD (stage 3b or worse) 1
• For hospitalized patients with renal impairment or elderly patients (>65 years), use lower doses of 0.1-0.25 units/kg/day 3
• Consider changing timing from bedtime to morning to reduce nocturnal hypoglycemia risk 1

Titration Strategy in Renal Impairment

• Target fasting glucose: 90-150 mg/dL (rather than the tighter 80-130 mg/dL used in patients without renal impairment) 1
• If 50% of fasting values over one week exceed goal: increase dose by 2 units 1
• If more than 2 fasting values per week are below 80 mg/dL: decrease dose by 2 units 1
• Implement close glucose monitoring with fasting finger-stick tests to promptly detect hypoglycemia 1

Standard Titration for Patients WITHOUT Renal Impairment

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

Critical Threshold: When to Add Prandial Insulin

• When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, stop escalating basal insulin and add prandial insulin instead 3, 4
• Clinical signals of overbasalization include: basal dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability 3
• Start with 4 units of rapid-acting insulin before the largest meal, or use 10% of the current basal dose 3, 4

Foundation Therapy

• Continue metformin unless contraindicated (such as eGFR <30 mL/min/1.73m²), as metformin reduces insulin requirements and provides complementary glucose-lowering effects 3, 4
• In patients with renal impairment, metformin may need to be discontinued or dose-adjusted based on eGFR 4

Administration Guidelines

• Administer insulin glargine subcutaneously once daily at the same time every day 2
• Inject into the abdominal area, thigh, or deltoid, rotating injection sites within the same region 2
• Do not administer intravenously, via insulin pump, or mix with other insulins 2
• Visually inspect for particulate matter; use only if clear and colorless 2

Safety Considerations in Renal Impairment

• Check for symptoms of hypoglycemia more frequently, as awareness may be blunted in older adults with renal impairment 1
• Assess for falls, cognitive changes, or unexplained symptoms that may indicate unrecognized hypoglycemia 1
• The convergence of renal impairment and insulin therapy creates a high-risk scenario where conservative dosing and relaxed glycemic targets are medically necessary 1

Common Pitfalls to Avoid

• Do not use standard dosing (0.1-0.2 units/kg/day) in patients with significant renal impairment without dose reduction 1
• Do not delay insulin initiation in patients not achieving glycemic goals with oral medications 3, 4
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia 3, 4
• Do not discontinue metformin abruptly when starting insulin unless contraindicated by renal function 3, 4