What is the recommended approach to initiating insulin therapy in an 89-year-old patient with chronic kidney disease stage 3?

Initiating Insulin in an 89-Year-Old with CKD Stage 3

Start with insulin glargine 5 units once daily at bedtime, then titrate by 1–2 units every 3 days based on fasting glucose, targeting 110–130 mg/dL to balance efficacy against hypoglycemia risk in this vulnerable population. 1, 2

---

Initial Dose Selection

• Begin with 5 units of insulin glargine (Lantus) subcutaneously once daily at bedtime rather than the standard 10 units or 0.1–0.2 units/kg, because older adults (>65 years) with renal impairment require lower starting doses to minimize hypoglycemia risk. 1, 2
• The standard recommendation of 10 units or 0.1–0.2 units/kg/day applies to younger, healthier patients; this 89-year-old with CKD Stage 3 falls into a high-risk category requiring dose reduction. 1, 2
• CKD Stage 3 (eGFR 30–59 mL/min/1.73 m²) reduces insulin clearance by approximately 30–50%, prolonging insulin action and increasing hypoglycemia risk, which justifies the conservative starting dose. 3, 4

---

Rationale for Conservative Dosing in This Population

• Older adults (>65 years) have increased insulin sensitivity due to reduced muscle mass, decreased hepatic gluconeogenesis, and impaired counterregulatory hormone responses, making them more prone to severe hypoglycemia. 1, 3
• CKD Stage 3 impairs insulin degradation, as the kidney normally clears 30–80% of circulating insulin; reduced clearance means insulin remains active longer, necessitating lower doses. 3
• Hypoglycemia in older adults with CKD is associated with increased mortality, falls, cognitive impairment, and cardiovascular events, making prevention the top priority. 1, 3
• Once-daily basal insulin is the preferred regimen for older adults because it minimizes complexity, reduces injection burden, and lowers hypoglycemia risk compared to multiple daily injections. 1

---

Glycemic Targets for This Patient

• Target fasting glucose of 110–130 mg/dL rather than the standard 80–130 mg/dL, because tighter targets increase hypoglycemia risk without mortality benefit in older adults with multiple comorbidities. 1, 3
• Aim for HbA1c of 7.5–8.0% rather than <7%, as very low HbA1c levels are associated with increased mortality in older adults and those with CKD, creating a U-shaped mortality curve. 1, 3
• Avoid aggressive glycemic targets that prioritize HbA1c reduction over quality of life and hypoglycemia prevention in this population. 1

---

Titration Protocol

• Increase insulin glargine by 1–2 units every 3 days based on fasting glucose measurements, using the following algorithm: 1, 2, 5
  • If fasting glucose is 140–179 mg/dL, increase by 1 unit every 3 days.
  • If fasting glucose is ≥180 mg/dL, increase by 2 units every 3 days.
  • If fasting glucose is <110 mg/dL on two or more occasions, decrease by 1–2 units immediately.
• Check fasting glucose daily during titration to guide dose adjustments and detect hypoglycemia early. 1, 2
• Reassess the insulin dose every 2 weeks rather than every 3 days in older adults with CKD, as slower titration reduces hypoglycemia risk. 1

---

Monitoring Requirements

• Daily fasting glucose checks are essential during the first 2–4 weeks of titration to guide dose adjustments. 1, 2
• Monitor for hypoglycemia symptoms (confusion, sweating, tremor, dizziness) at every visit, as older adults often have hypoglycemia unawareness. 1, 3
• Check HbA1c every 3 months to assess overall glycemic control, but do not rely solely on HbA1c in CKD patients, as it may be falsely low due to anemia and reduced red blood cell lifespan. 3
• Assess renal function (eGFR, creatinine) every 3–6 months, as declining kidney function will require further insulin dose reductions. 3, 4
• Consider continuous glucose monitoring (CGM) if available, as it detects asymptomatic and nocturnal hypoglycemia more effectively than fingerstick testing in older adults with CKD. 3

---

Adjustments for Declining Renal Function

• If eGFR declines to <30 mL/min/1.73 m² (CKD Stage 4–5), reduce total daily insulin dose by an additional 25–35% to prevent severe hypoglycemia. 3
• If the patient progresses to dialysis, reduce total daily insulin dose by 35–40% for type 1 diabetes or 50% for type 2 diabetes, as dialysis further impairs insulin clearance. 3
• Reduce basal insulin by 25% on pre-dialysis days if the patient starts hemodialysis, as glucose levels drop progressively during dialysis sessions. 3

---

Combination Therapy Considerations

• Continue metformin at the maximum tolerated dose (up to 1000 mg twice daily) if eGFR is ≥30 mL/min/1.73 m², as metformin reduces insulin requirements by 20–30% and improves glycemic control. 1, 2
• Discontinue metformin if eGFR falls below 30 mL/min/1.73 m² due to increased risk of lactic acidosis. 2
• Consider adding a GLP-1 receptor agonist (e.g., semaglutide) if basal insulin alone does not achieve targets, as it provides additional glucose lowering with lower hypoglycemia risk and weight loss rather than weight gain. 1, 2
• Avoid sulfonylureas in older adults with CKD, as they cause prolonged hypoglycemia due to reduced renal clearance. 2

---

Critical Pitfalls to Avoid

• Do not start with 10 units or 0.1–0.2 units/kg/day in this patient, as standard dosing increases hypoglycemia risk in older adults with CKD. 1, 2, 3
• Do not target fasting glucose <100 mg/dL or HbA1c <7%, as aggressive targets increase hypoglycemia risk without mortality benefit in this population. 1, 3
• Do not rely solely on HbA1c for glycemic monitoring in CKD patients, as it underestimates mean glucose levels and correlates poorly with actual glycemic control. 3
• Do not delay insulin dose reduction if hypoglycemia occurs; reduce the dose by 10–20% immediately and reassess within 3 days. 1, 2
• Do not initiate multiple daily injections (basal-bolus regimen) in this patient, as it increases complexity, hypoglycemia risk, and treatment burden without clear benefit. 1
• Do not discontinue metformin abruptly when starting insulin unless contraindicated, as the combination provides superior glycemic control with less weight gain. 2

---

Hypoglycemia Prevention and Management

• Treat any glucose <70 mg/dL immediately with 15 g of fast-acting carbohydrate (e.g., 4 glucose tablets, 4 oz juice), recheck in 15 minutes, and repeat if needed. 1, 2
• Reduce insulin dose by 10–20% if hypoglycemia occurs without an obvious cause (e.g., missed meal, increased activity). 1, 2
• Educate the patient and caregivers on hypoglycemia recognition, treatment, and when to contact the provider. 1
• Provide a glucagon emergency kit and train caregivers on its use for severe hypoglycemia. 1

---

Simplification and Deprescribing Considerations

• Simplify the insulin regimen by using once-daily basal insulin rather than multiple daily injections, as complexity increases errors and non-adherence in older adults. 1
• Consider deprescribing insulin if the patient develops advanced dementia, limited life expectancy (<1 year), or severe functional decline, as the risks of hypoglycemia outweigh the benefits of tight glycemic control. 1
• Adjust insulin doses every 2 weeks rather than every 3 days in older adults with multiple comorbidities, as slower titration reduces hypoglycemia risk. 1

---

Expected Clinical Outcomes

• With conservative dosing and titration, 60–70% of older adults with CKD achieve fasting glucose 110–130 mg/dL within 4–8 weeks without severe hypoglycemia. 1, 2
• HbA1c reduction of 1.0–1.5% is achievable with basal insulin alone in this population, which is sufficient to reduce microvascular complications without increasing hypoglycemia risk. 1, 2
• Hypoglycemia rates remain <5% when conservative dosing and titration protocols are followed in older adults with CKD. 1, 3