What basal insulin (insulin glargine) dose, carbohydrate‑to‑insulin ratio, and correction factor (insulin sensitivity factor) are appropriate for a 57‑year‑old, 57‑kg man with type 2 diabetes, impaired renal function (creatinine 1.27 mg/dL, eGFR ≈ 66 mL/min), large‑cell lymphoma, acute urinary‑tract infection, currently on empagliflozin, metformin, sitagliptin, and glipizide, who is receiving 10 U insulin glargine daily and a rapid‑acting insulin dose of 1 U per 15 g carbohydrate but has post‑prandial glucose values of 281 mg/dL and 514 mg/dL?

Insulin Dosing Recommendations for Hospitalized Patient with Type 2 Diabetes and Acute Illness

This patient requires immediate discontinuation of all oral diabetes medications and transition to a scheduled basal-bolus insulin regimen with a starting total daily dose of approximately 17–29 units (0.3–0.5 units/kg/day), divided as 50% basal insulin glargine and 50% prandial rapid-acting insulin split among three meals.

Critical Medication Changes Required Immediately

Discontinue All Oral Agents During Acute Illness

• Stop Jardiance (empagliflozin) 25 mg immediately because SGLT2 inhibitors are contraindicated during acute illness, particularly with UTI and stress hyperglycemia, due to increased risk of euglycemic diabetic ketoacidosis and dehydration 1, 2, 3.
• Stop metformin 1000 mg BID immediately because the patient has impaired renal function (eGFR 66 mL/min) and acute illness (UTI), which increases lactic acidosis risk; metformin should be held during hospitalization and acute illness 4.
• Stop Januvia (sitagliptin) 100 mg because DPP-4 inhibitors provide minimal glucose-lowering during acute hyperglycemic crises and are ineffective when insulin is required 5.
• Stop glipizide 5 mg immediately because sulfonylureas cause unpredictable hypoglycemia during acute illness when oral intake is variable and significantly increase hypoglycemia risk when combined with insulin 4, 5.

Why Sliding-Scale Insulin Alone Is Dangerous

• The patient's glucose escalation from 281 mg/dL to 514 mg/dL despite receiving correction insulin demonstrates complete failure of sliding-scale monotherapy, which is condemned by all major diabetes guidelines 5.
• Only 38% of patients on sliding-scale alone achieve mean glucose <140 mg/dL versus 68% with basal-bolus therapy, with no difference in hypoglycemia rates 5.
• The 0.5 units/hour insulin drip overnight indicates the patient required approximately 12 units of insulin over 24 hours just to control the acute hyperglycemia, confirming inadequate scheduled insulin 5.

Recommended Insulin Regimen

Calculate Total Daily Dose (TDD)

• For a 57 kg patient with severe hyperglycemia (glucose 281–514 mg/dL) and acute illness, start with 0.3–0.5 units/kg/day 5.
• TDD = 0.3 × 57 kg = 17 units/day (conservative, given age 57 and renal impairment) to 0.5 × 57 kg = 29 units/day (more aggressive given severe hyperglycemia) 5.
• Recommended starting TDD: 20–25 units/day (middle range accounting for acute illness and renal impairment) 5.

Basal Insulin (Insulin Glargine/Lantus)

• Give 10–12 units of insulin glargine once daily at bedtime (50% of TDD of 20–25 units) 5.
• Administer at the same time each evening (preferably 20:00 h/8 PM) 5.
• Titrate basal insulin every 3 days based on fasting glucose patterns 5:
  • If fasting glucose 140–179 mg/dL: increase by 2 units
  • If fasting glucose ≥180 mg/dL: increase by 4 units
  • Target fasting glucose 80–130 mg/dL
  • If glucose <70 mg/dL occurs, reduce dose by 10–20% immediately

Prandial Insulin (Rapid-Acting Insulin)

• Give 3–4 units of rapid-acting insulin (lispro, aspart, or glulisine) before each of three meals (50% of TDD divided by 3 meals) 5.
• Administer 0–15 minutes before meals for optimal postprandial control 5.
• Titrate prandial insulin every 3 days based on 2-hour postprandial glucose 5:
  • If postprandial glucose consistently >180 mg/dL: increase by 1–2 units
  • Target postprandial glucose <180 mg/dL
  • If hypoglycemia occurs, reduce by 10–20%

Carbohydrate-to-Insulin Ratio (Carb Ratio)

• Starting ratio: 1 unit per 15 grams of carbohydrate 5.
• Calculate using formula: 500 ÷ TDD = 500 ÷ 23 = approximately 22 grams per unit, but start conservatively at 1:15 ratio given renal impairment 5.
• Adjust based on 2-hour postprandial glucose readings:
  • If postprandial glucose consistently >180 mg/dL: tighten ratio to 1:12 or 1:10
  • If postprandial glucose <70 mg/dL: loosen ratio to 1:18 or 1:20

Correction Factor (Insulin Sensitivity Factor)

• Starting correction factor: 1 unit lowers glucose by 50 mg/dL 5.
• Calculate using formula: 1500 ÷ TDD = 1500 ÷ 23 = approximately 65 mg/dL per unit, but start conservatively at 1:50 given renal impairment and risk of hypoglycemia 5.
• Correction dose = (Current glucose – Target glucose of 125 mg/dL) ÷ 50 5.
• Example: If pre-meal glucose is 225 mg/dL, correction dose = (225 – 125) ÷ 50 = 2 units added to meal insulin.

Correction Insulin Protocol (Supplemental to Scheduled Doses)

• Add 2 units of rapid-acting insulin when pre-meal glucose >250 mg/dL 5.
• Add 4 units of rapid-acting insulin when pre-meal glucose >350 mg/dL 5.
• Never give rapid-acting insulin at bedtime as sole correction dose due to nocturnal hypoglycemia risk 5.

Special Considerations for This Patient

Renal Impairment (Cr 1.27, eGFR 66 mL/min)

• Use the lower end of dosing ranges (0.3 units/kg/day rather than 0.5 units/kg/day) because insulin clearance decreases with declining kidney function 5.
• Monitor glucose more frequently (before each meal and at bedtime) because hypoglycemia risk increases with renal impairment 5.
• Titrate conservatively with smaller increments (1–2 units every 3 days rather than 4 units) 5.
• Empagliflozin exposure increases 43.8% with eGFR 30–60 mL/min, making it less effective and potentially more harmful during acute illness 6.

Acute Illness (UTI, Large Cell Lymphoma)

• Acute illness and infection increase insulin resistance, requiring higher insulin doses than outpatient baseline 5.
• The patient's insulin requirements will likely decrease by 20–30% once the UTI resolves and acute stress subsides 5.
• Check urine or blood ketones immediately given glucose >300 mg/dL to rule out ketoacidosis, especially since SGLT2 inhibitors increase ketoacidosis risk 7, 1.

Age and Frailty Considerations

• At age 57 with BMI 20 (lean body habitus) and cancer diagnosis, this patient may have increased insulin sensitivity and higher hypoglycemia risk 4.
• Individualized A1C target of 7.5–8.5% may be more appropriate than <7% given complex medical conditions and limited life expectancy with large cell lymphoma 4.

Monitoring Requirements

Glucose Monitoring Frequency

• Check point-of-care glucose before each meal and at bedtime (4 times daily minimum) 5.
• Check 2-hour postprandial glucose after the largest meal to guide prandial insulin adjustments 5.
• Check glucose every 4–6 hours if NPO or poor oral intake 5.

Laboratory Monitoring

• Recheck basic metabolic panel daily while hospitalized to monitor potassium (insulin drives potassium intracellularly) and renal function 5, 7.
• Check A1C every 3 months once discharged until target achieved 8.

Hypoglycemia Protocol

• Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate, recheck in 15 minutes, and repeat if needed 5.
• Reduce the implicated insulin dose by 10–20% if hypoglycemia occurs without clear cause 5.
• Prescribe glucagon for emergency use and educate family members on administration 8.

Critical Pitfalls to Avoid

• Do not continue sliding-scale insulin as monotherapy—this approach is ineffective and dangerous, leading to glucose fluctuations between 281 and 514 mg/dL as demonstrated in this patient 5.
• Do not restart oral diabetes medications until the patient is clinically stable, eating normally, and the UTI has resolved; metformin requires stable renal function and Jardiance should be avoided during acute illness 4, 1, 2.
• Do not delay transition to scheduled basal-bolus insulin—the patient's glucose of 514 mg/dL signals complete inadequacy of the current regimen 5.
• Do not give rapid-acting insulin at bedtime as a sole correction dose, which markedly raises nocturnal hypoglycemia risk 5.
• Do not continue escalating basal insulin beyond 0.5 units/kg/day (29 units) without adding or intensifying prandial insulin, as this causes "overbasalization" with increased hypoglycemia 5.
• Do not assume the 10 units of Lantus previously given was adequate—this represents only 0.18 units/kg/day, far below the 0.3–0.5 units/kg/day needed for severe hyperglycemia 5.

Expected Outcomes

• With appropriate basal-bolus therapy at weight-based dosing, 68% of patients achieve mean glucose <140 mg/dL versus only 38% with sliding-scale alone 5.
• Expect glucose to decline by 50–75 mg/dL per hour with proper insulin dosing 7.
• A1C reduction of 2–3% is achievable over 3–6 months with proper insulin intensification 5.
• Once the UTI resolves and acute illness subsides, insulin requirements will decrease by 20–30%, requiring dose reduction to prevent hypoglycemia 5.

Discharge Planning

• Restart metformin 1000 mg BID only after renal function stabilizes (eGFR >45 mL/min) and patient is eating normally 4.
• Consider restarting Jardiance 25 mg only after complete resolution of acute illness, stable renal function (eGFR >45 mL/min), and patient education about ketoacidosis risk 1, 2, 3.
• Discontinue glipizide permanently due to high hypoglycemia risk when combined with insulin 4.
• Provide comprehensive diabetes education on insulin injection technique, glucose monitoring, hypoglycemia recognition/treatment, sick-day management, and insulin storage 5.
• Simplify the insulin regimen if the patient has difficulty with multiple daily injections, potentially using a basal-plus-correction approach (basal insulin plus correction doses only) rather than full basal-bolus 4, 5.