What is the recommended approach for insulin initiation in patients with diabetes?

Insulin Initiation in Diabetes

Starting Basal Insulin in Type 2 Diabetes

For insulin-naive patients with type 2 diabetes, initiate basal insulin at 10 units once daily or 0.1-0.2 units/kg/day, administered at the same time each day, and continue metformin unless contraindicated. 1, 2, 3

Initial Dosing Algorithm

• Standard initiation: Begin with 10 units once daily for most patients with mild-to-moderate hyperglycemia 1, 2, 4
• Weight-based dosing: Use 0.1-0.2 units/kg/day when tailoring to body weight, with higher doses (0.2 units/kg) for more severe hyperglycemia 1, 3
• Severe hyperglycemia (A1C ≥9% or glucose ≥300-350 mg/dL): Consider starting with 0.3-0.5 units/kg/day as total daily dose, split between basal and prandial insulin, rather than basal insulin alone 1, 2, 4
• Symptomatic/catabolic features with A1C 10-12%: Start basal-bolus insulin immediately, not basal insulin alone 1, 2

Titration Protocol

Increase basal insulin by 2-4 units every 3 days until fasting glucose reaches 80-130 mg/dL, using patient self-titration algorithms to improve glycemic control. 1, 2, 4

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

Critical Threshold: Recognizing Overbasalization

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin rather than continuing to escalate basal insulin alone. 1, 2, 4

Clinical signals of overbasalization include: 2, 4

• Basal insulin dose >0.5 units/kg/day
• Bedtime-to-morning glucose differential ≥50 mg/dL
• Hypoglycemia episodes
• High glucose variability

Foundation Therapy Considerations

• Continue metformin when adding or intensifying insulin therapy unless contraindicated 1, 2, 4
• Basal insulin is typically prescribed with metformin and possibly one additional non-insulin agent 1, 2
• Consider adding a GLP-1 receptor agonist to basal insulin to address postprandial hyperglycemia while minimizing weight gain and hypoglycemia risk 2, 4

Starting Insulin in Type 1 Diabetes

For patients with type 1 diabetes, initiate with a total daily dose of 0.5 units/kg/day, giving approximately 50% as basal insulin once daily and 50% as prandial insulin divided among meals. 1, 4, 3

Type 1 Diabetes Dosing Specifics

• Total daily insulin requirements typically range from 0.4-1.0 units/kg/day 1, 4
• For metabolically stable patients: use 0.5 units/kg/day as the typical starting point 1, 4
• Approximately one-third of total daily insulin requirements should be basal insulin, with short-acting premeal insulin satisfying the remainder 3
• Higher doses are required during puberty, pregnancy, and medical illness 1, 4
• Patients in the honeymoon phase may require lower doses of 0.2-0.6 units/kg/day 4

Administration Requirements

• Type 1 diabetes patients must use basal insulin concomitantly with short-acting insulin 3
• Prandial insulin should be administered 0-15 minutes before meals 1, 4, 5
• Educate patients on adjusting prandial insulin based on carbohydrate intake, premeal glucose levels, and anticipated activity 1

Essential Patient Education

Comprehensive education regarding self-monitoring of blood glucose, diet, hypoglycemia recognition and treatment, and proper injection technique is critically important for any patient using insulin. 1, 2, 4

Injection Technique

• Administer subcutaneously into the abdomen, thigh, or deltoid 3
• Rotate injection sites within the same region to reduce risk of lipodystrophy and localized cutaneous amyloidosis 3, 5
• Use 4-mm pen needles as first-line choice—they are safe, effective, and less painful 5
• Avoid injecting into areas of lipohypertrophy, as this distorts insulin absorption 3, 5

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1, 2, 4
• Increase frequency of blood glucose monitoring during any changes to insulin regimen 3
• Assess adequacy of insulin dose at every clinical visit 2, 4

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications—this prolongs hyperglycemia exposure and increases complication risk 2, 4
• Do not use insulin as a threat or describe it as personal failure; explain the progressive nature of type 2 diabetes objectively 1
• Avoid continuing to escalate basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to overbasalization with increased hypoglycemia risk and suboptimal control 1, 2, 4
• Do not abruptly discontinue oral medications when starting insulin; continue metformin unless contraindicated 2, 4, 5
• Never administer insulin glargine intravenously or via insulin pump 3
• Do not dilute or mix insulin glargine with any other insulin or solution due to its low pH 4, 3

Special Clinical Situations

Hospitalized Patients

• For insulin-naive or low-dose insulin patients: start 0.3-0.5 units/kg/day total daily dose, with half as basal insulin 4
• For patients on high-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% upon admission to prevent hypoglycemia 4
• Use lower doses (0.1-0.25 units/kg/day) for high-risk patients: elderly (>65 years), renal failure, or poor oral intake 4

Switching from Other Insulins

• From once-daily insulin glargine 300 units/mL: start at 80% of the discontinued dose 3
• From once-daily NPH insulin: start at the same dose 3
• From twice-daily NPH insulin: start at 80% of total NPH dose 3