Converting Basal-Bolus to Mixtard on Discharge
For most patients with type 2 diabetes on basal-bolus insulin during hospitalization, converting to Mixtard (biphasic insulin) at discharge is generally NOT recommended due to significantly higher hypoglycemia rates and inferior glycemic control compared to continuing basal-bolus therapy. 1, 2
Critical Evidence Against Mixtard Conversion
Randomized trials demonstrate that premixed insulin regimens (like Mixtard) have unacceptably high rates of iatrogenic hypoglycemia in hospital settings and should be avoided. 2 The evidence shows:
- Basal-bolus therapy provides better glycemic control with reduced hospital complications compared to premixed insulin regimens 2
- Premixed insulin has significantly increased hypoglycemia rates 2
- Guidelines explicitly recommend against using premixed insulin in hospitalized patients 2
Recommended Discharge Strategy Based on HbA1c
For Patients with HbA1c <7.5-8% 1
Resume the patient's prehospitalization treatment regimen (oral agents and/or insulin) at the doses used in hospital. 1
- For Type 1 diabetes: Continue basal-bolus insulin at hospital doses 1
- For Type 2 diabetes: Can transition back to oral agents plus basal insulin at 50% of hospital basal dose 1
- Schedule follow-up with treating physician at one month 1
For Patients with HbA1c 8-10% 1
Discharge on oral agents plus basal insulin at 50% of the hospital basal dose. 1
- Continue metformin unless contraindicated 1
- Consider adding DPP-4 inhibitors as an alternative to full basal-bolus regimen 1
- Schedule distant consultation with diabetologist 1
For Patients with HbA1c >9-10% 1
Continue the basal-bolus regimen and request diabetologist advice before discharge for possible hospitalization in specialized service. 1
- Patients with HbA1c >10% should be discharged on basal-bolus regimen or combination of preadmission oral agents plus 80% of hospital basal insulin dose 1
- Do not simplify to Mixtard in this population 2
If Mixtard Conversion Is Absolutely Necessary (Not Recommended)
If institutional or patient factors mandate Mixtard use despite the evidence against it, calculate as follows:
Conversion Calculation
Calculate total daily insulin dose (TDD) from current basal-bolus regimen 2, 3
- Add all basal + all bolus insulin units from past 24 hours
Reduce TDD by 20% to prevent hypoglycemia 2
- Mixtard has less predictable pharmacokinetics than modern analogs
Split the reduced TDD 3
- Give 2/3 of total dose before breakfast
- Give 1/3 of total dose before dinner
- Each Mixtard injection contains 30% rapid-acting and 70% intermediate-acting insulin 3
Example Calculation
- Patient on glargine 20 units + aspart 6 units TID = 38 units TDD
- Reduce by 20%: 38 × 0.8 = 30 units
- Mixtard 20 units before breakfast + 10 units before dinner
Critical Pitfalls to Avoid
Never abruptly discontinue oral medications when converting insulin regimens due to risk of rebound hyperglycemia. 3
Never use Mixtard in Type 1 diabetes patients - they require basal-bolus insulin with separate basal and prandial components for physiologic replacement. 1, 3
Avoid Mixtard in patients with:
- Variable meal timing or carbohydrate intake 3
- History of severe hypoglycemia 2
- Elderly patients (>65 years) with multiple comorbidities 1, 4
- Renal impairment 2
Monitoring Requirements Post-Discharge
- Check fasting and pre-dinner blood glucose daily for first 2 weeks 3, 5
- Recheck HbA1c in 3 months 6
- Provide clear hypoglycemia recognition and treatment education 1
- Ensure patient understands fixed meal timing requirements with Mixtard 3
Superior Alternative: Continue Basal-Bolus or Simplify to Basal-Only
For Type 2 diabetes patients who need simplification, transition to basal insulin alone (not Mixtard) plus oral agents. 1, 5