What is the recommended starting dose and administration protocol for Mixtard (insulin) in a typical adult patient with type 2 diabetes?

Starting Mixtard Insulin in Type 2 Diabetes

Initial Dosing Strategy

For insulin-naive patients with type 2 diabetes, start Mixtard at 10 units twice daily (before breakfast and before dinner), or use weight-based dosing of 0.1-0.2 units/kg/day divided into two injections. 1

• For patients with severe hyperglycemia (A1C ≥9%, blood glucose ≥300 mg/dL, or symptomatic/catabolic features), consider higher starting doses of 0.3-0.4 units/kg/day divided between morning and evening injections 2, 1
• Continue metformin unless contraindicated when initiating Mixtard, as this reduces total insulin requirements and provides complementary glucose-lowering effects 1

Mixtard Formulation Selection

Mixtard 30 (30% regular insulin/70% NPH) is the standard formulation for most patients, while Mixtard 50 (50% regular/50% NPH) should be reserved for patients with significant post-breakfast hyperglycemia. 3

• Mixtard 50 provides more rapid-acting insulin coverage, resulting in greater blood glucose decline from pre-breakfast to pre-lunch compared to Mixtard 30 3
• The choice between formulations should be based on the patient's specific glycemic pattern, with Mixtard 50 more appropriate for post-breakfast hyperglycemic patients 3

Dose Titration Protocol

Increase the total daily dose by 2-4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL, distributing the dose equally between morning and evening injections. 1

• If fasting glucose is 140-179 mg/dL, increase by 2 units every 3 days 1
• If fasting glucose is ≥180 mg/dL, increase by 4 units every 3 days 1
• If more than 2 fasting glucose values per week are <80 mg/dL, decrease the dose by 2 units 1
• If hypoglycemia occurs, reduce the dose by 10-20% immediately 1

Critical Threshold for Regimen Change

When the total daily dose of Mixtard exceeds 0.5 units/kg/day and A1C remains above target after 3-6 months, transition to a basal-bolus regimen rather than continuing to escalate premixed insulin. 1

• Continuing to increase premixed insulin beyond this threshold leads to "overbasalization" with increased hypoglycemia risk and suboptimal postprandial control 1
• Clinical signals indicating need for regimen change include: basal dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, recurrent hypoglycemia, and high glucose variability 1

Monitoring Requirements

Patients must perform daily self-monitoring of blood glucose before breakfast, before lunch, and at bedtime during the titration phase. 3

• Reassess the insulin dose every 3 days during active titration 1
• Check A1C every 3 months during intensive titration 1
• Once stable, continue monitoring fasting glucose and reassess every 3-6 months 1

Administration Technique

Mixtard should be injected 0-15 minutes before meals using the shortest available needles (4-mm pen needles or 6-mm syringe needles) to minimize pain and avoid intramuscular injection. 4

• Rotate injection sites systematically to prevent lipohypertrophy, which distorts insulin absorption 4
• Do not inject into areas of lipohypertrophy 4
• Mixtard should not be mixed with other insulins due to its formulation 4

Common Pitfalls to Avoid

Do not delay insulin initiation in patients not achieving glycemic goals with oral medications, as this prolongs exposure to hyperglycemia and increases complication risk. 1

• Do not abruptly discontinue oral medications when starting Mixtard—continue metformin unless contraindicated 4
• Do not continue escalating Mixtard beyond 0.5-1.0 units/kg/day without transitioning to basal-bolus therapy, as this causes overbasalization with increased hypoglycemia and suboptimal control 1
• Do not use premixed insulin in hospitalized patients due to unacceptably high rates of iatrogenic hypoglycemia—use basal-bolus regimens instead 1

Special Populations Requiring Dose Adjustment

For elderly patients (>65 years), those with renal impairment (eGFR <50 mL/min/1.73 m²), or patients with poor oral intake, start with lower doses of 0.1-0.25 units/kg/day to prevent hypoglycemia. 1

• For hospitalized patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% upon admission 1

Patient Education Essentials

All patients starting Mixtard must receive structured education on hypoglycemia recognition and treatment, proper injection technique, site rotation, self-monitoring of blood glucose, "sick day" management, and insulin storage. 1, 5

• Provide patients with self-titration algorithms based on self-monitoring results to improve glycemic control 1
• Educate patients that hypoglycemia should be treated with 15 grams of fast-acting carbohydrate when blood glucose is ≤70 mg/dL 1