Converting from Lantus BID + Lispro to 70/30 Insulin
Recommended Starting Dose
Start with 70/30 insulin at approximately 38 units before breakfast and 19 units before dinner, representing an 80% conversion of the current total daily dose to account for the higher hypoglycemia risk with premixed insulin. 1
Dose Calculation Rationale
The patient's current total daily insulin dose is 77 units: Lantus 30 units twice daily (60 units) + insulin lispro approximately 17 units daily 1
When converting to 70/30 insulin from a basal-bolus regimen, the Endocrine Society recommends reducing the total daily dose by 20% if currently taking more than 0.6 units/kg/day to prevent hypoglycemia 1
This patient's regimen exceeds typical dosing thresholds, warranting the 20% reduction: 77 units × 0.80 = approximately 62 units total daily dose 1
The American Diabetes Association recommends distributing the total daily dose as 2/3 in the morning (approximately 41 units) and 1/3 in the evening (approximately 21 units) to minimize nocturnal hypoglycemia risk 2
However, given the high baseline dose and hypoglycemia risk, start more conservatively at 38 units before breakfast and 19 units before dinner 1, 2
Critical Safety Considerations
Premixed 70/30 insulin carries a 4-6 times higher risk of hypoglycemia compared to basal-bolus regimens, making dose reduction essential 1
The American Geriatrics Society recommends using lower starting doses for patients at high risk, such as those aged >65 years, with renal failure, or with poor oral intake 1
Administer 70/30 insulin 30 minutes before breakfast and dinner, not at mealtime like lispro 1, 3
Patients must eat similar amounts of carbohydrates at consistent meal times to match the fixed insulin doses 1
Titration Protocol
Adjust doses every 2-3 days based on self-monitoring of blood glucose, targeting fasting glucose of 90-150 mg/dL 2
If ≥50% of fasting values exceed goal: increase the evening dose by 2 units 1
If >2 fasting values per week are <80 mg/dL: decrease the corresponding dose by 2 units 1
For any hypoglycemia without clear cause, reduce the corresponding dose by 10-20% immediately 2
Essential Monitoring Requirements
Increase blood glucose monitoring frequency to at least 4 times daily during the first 1-2 weeks after conversion to monitor for hypoglycemia risk 2
Check fasting glucose, pre-lunch, pre-dinner, and bedtime glucose to assess adequacy of both the NPH and regular insulin components 4
Foundation Therapy Continuation
Continue metformin unless contraindicated when making this insulin transition 1
If A1C is above goal and the patient is not already on a GLP-1 RA, consider adding this class in combination with insulin rather than continuing to escalate premixed insulin doses 1
Common Pitfalls to Avoid
Do not use equal morning and evening doses (38.5 units each), as this substantially increases nocturnal hypoglycemia risk 2
The American College of Endocrinology warns against continuing to escalate 70/30 doses indefinitely if A1C remains above target 1
When basal insulin exceeds 0.5 units/kg/day, consider adding a GLP-1 receptor agonist or converting back to a basal-bolus regimen rather than continuing to increase premixed insulin 1
The European Association for the Study of Diabetes recommends against using 70/30 insulin in patients with unpredictable eating patterns or those requiring flexible dosing 1
When This Regimen May Not Be Appropriate
If the patient has unpredictable eating patterns, highly variable carbohydrate intake, or requires precise insulin dosing flexibility, 70/30 insulin is not the optimal choice, and separate basal and prandial insulins should be continued 2
Randomized trials show that basal-bolus therapy provides better glycemic control with reduced hospital complications compared to premixed insulin regimens, which have significantly increased hypoglycemia rates 5