How should I manage an adult with type 2 diabetes on premixed insulin (Mixtard, insulin human 30% rapid‑acting/70% intermediate‑acting) 24 units twice daily who deliberately skips meals and has elevated glycated hemoglobin?

Management of Type 2 Diabetes with Deliberate Meal Skipping on Premixed Insulin

Immediately discontinue Mixtard 70/30 and transition to a basal-bolus insulin regimen with insulin glargine plus rapid-acting insulin before meals, because premixed insulin carries an unacceptably high risk of severe hypoglycemia when meals are skipped and lacks the flexibility required for irregular eating patterns. 1

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Why Mixtard 70/30 Is Inappropriate for This Patient

• Premixed insulin 70/30 is explicitly contraindicated in patients with irregular meal timing or deliberate meal skipping because the fixed 30% rapid-acting component will cause severe hypoglycemia when food is not consumed. 1
• The rigid dosing schedule of premixed insulin requires consistent meal timing and carbohydrate intake, which this patient is deliberately not following. 1
• Premixed insulin formulations carry an unacceptably high rate of iatrogenic hypoglycemia (64% in hospitalized patients versus 24% with basal-bolus therapy), and this risk is magnified when meals are skipped. 2, 1
• The HbA1c of 11.5% indicates complete therapeutic failure of the current regimen, requiring immediate regimen restructuring rather than dose adjustment. 2

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Immediate Regimen Change: Transition to Basal-Bolus Therapy

Calculate Total Daily Insulin Dose

• Start with 0.3–0.5 units/kg/day as the total daily dose given the severe hyperglycemia (HbA1c 11.5%). 2, 3
• For a typical adult (e.g., 70 kg), this equals 21–35 units/day total. 2, 3

Distribute Insulin Doses

• Allocate 50% to basal insulin (insulin glargine) given once daily at bedtime → ≈11–18 units. 2, 3, 1
• Allocate 50% to rapid-acting insulin (lispro or aspart) divided among meals only when the patient actually eats → ≈11–18 units total, split as ≈4–6 units per meal. 2, 3, 1
• Critical advantage: Basal insulin provides continuous glucose control independent of meals, while rapid-acting insulin is given only when food is consumed, eliminating hypoglycemia risk from skipped meals. 2, 1

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Addressing the Meal-Skipping Behavior

Patient Education Priorities

• Explain that basal insulin (glargine) must be taken daily regardless of eating because it suppresses hepatic glucose production continuously, preventing hyperglycemia and ketosis even when fasting. 2
• Rapid-acting insulin is administered 0–15 minutes before meals only when the patient eats; if a meal is skipped, the rapid-acting dose for that meal is omitted entirely. 2, 3
• Emphasize that deliberate meal skipping on the current Mixtard regimen is causing the severe hyperglycemia (HbA1c 11.5%) because the patient is likely omitting insulin doses to avoid hypoglycemia, resulting in uncontrolled glucose. 2

Behavioral Assessment

• Determine the reason for meal skipping: financial constraints, depression, eating disorder, intentional weight loss, or lack of understanding. 2
• If meal skipping is intentional for weight management, consider adding a GLP-1 receptor agonist (e.g., semaglutide) to basal insulin instead of prandial insulin, as this provides postprandial control with weight loss rather than weight gain. 2
• If meal skipping is due to financial constraints or food insecurity, refer to social services and diabetes self-management education immediately. 2

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Titration Protocols

Basal Insulin (Glargine) Titration

• Increase by 4 units every 3 days if fasting glucose ≥180 mg/dL. 2, 3
• Increase by 2 units every 3 days if fasting glucose is 140–179 mg/dL. 2, 3
• Target fasting glucose: 80–130 mg/dL. 2, 3
• Stop basal escalation when dose approaches 0.5 units/kg/day (≈35 units for a 70 kg patient) without achieving targets; at this point, intensify prandial insulin or add a GLP-1 receptor agonist. 2, 3

Prandial Insulin Titration (Only for Meals Actually Eaten)

• Increase each meal dose by 1–2 units every 3 days based on 2-hour postprandial glucose readings. 2, 3
• Target postprandial glucose <180 mg/dL. 2, 3
• If a meal is skipped, omit the rapid-acting dose entirely—this is the critical safety feature that premixed insulin lacks. 2, 1

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Monitoring Requirements

• Daily fasting glucose checks to guide basal insulin titration. 2, 3
• Pre-meal glucose before each meal to calculate correction doses when needed. 2, 3
• 2-hour postprandial glucose after meals that are eaten to assess prandial insulin adequacy. 2, 3
• HbA1c every 3 months during intensive titration; expect a reduction of 2–3% (from 11.5% to ≈8.5–9.5%) over 3–6 months with proper basal-bolus therapy. 2, 3

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Foundation Therapy: Continue Metformin

• Restart or maximize metformin to 2000 mg daily (1000 mg twice daily with meals) unless contraindicated. 2, 3
• Metformin reduces total insulin requirements by 20–30% and provides superior glycemic control when combined with insulin. 2, 3
• Never discontinue metformin when intensifying insulin therapy unless specific contraindications exist (e.g., renal impairment, acute illness). 2, 3

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Alternative: GLP-1 Receptor Agonist Instead of Prandial Insulin

• If meal skipping is intentional for weight management or if the patient refuses multiple daily injections, consider adding a GLP-1 receptor agonist (e.g., semaglutide 0.25 mg weekly, titrated to 1 mg weekly) to basal insulin instead of prandial insulin. 2
• GLP-1 receptor agonists provide postprandial glucose control with weight loss (versus weight gain with prandial insulin) and lower hypoglycemia risk. 2
• This combination (basal insulin + GLP-1 RA) is explicitly recommended by guidelines before advancing to prandial insulin in patients with irregular eating patterns. 2

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Critical Pitfalls to Avoid

• Never continue premixed insulin in a patient who deliberately skips meals—this is a recipe for severe hypoglycemia and therapeutic failure. 1
• Never increase Mixtard doses in response to high HbA1c when meals are being skipped; this will worsen hypoglycemia risk and perpetuate the cycle of dose omission. 2, 1
• Do not delay the transition to basal-bolus therapy when HbA1c is 11.5%; prolonged severe hyperglycemia increases complication risk exponentially. 2
• Never use sliding-scale insulin as monotherapy in place of scheduled basal-bolus therapy; this reactive approach is condemned by all major diabetes guidelines. 2, 3
• Do not administer rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk. 2, 3

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Expected Clinical Outcomes

• With properly implemented basal-bolus therapy, ≈68% of patients achieve mean glucose <140 mg/dL, versus ≈38% with inadequate regimens like premixed insulin used inappropriately. 2, 3
• HbA1c reduction of 2–3% (from 11.5% to ≈8.5–9.5%) is achievable within 3–6 months with intensive titration and behavioral support. 2, 3
• Basal-bolus therapy does not increase hypoglycemia incidence compared with premixed insulin when properly implemented, and it provides the flexibility required for irregular eating patterns. 2, 3

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Referral and Support

• Immediate referral to diabetes self-management education and support (DSMES) is essential to address meal-skipping behavior and teach proper insulin administration. 2
• Consider referral to endocrinology for HbA1c >9% with unstable glucose patterns. 2
• Screen for depression and eating disorders in patients who deliberately skip meals, as these are common comorbidities requiring concurrent treatment. 2