What is the recommended approach for initiating basal insulin therapy in a patient with diabetes?

How to Start Basal Insulin

Start basal insulin at 10 units once daily OR 0.1-0.2 units/kg body weight, administered at the same time each day, and continue metformin unless contraindicated. 1, 2, 3

Initial Dosing Strategy

Standard Starting Dose for Type 2 Diabetes

• For insulin-naive patients with type 2 diabetes: 10 units once daily OR 0.1-0.2 units/kg/day 1, 2, 3
• Administer subcutaneously at the same time every day—timing flexibility exists, but consistency is critical 1, 3
• Inject into the abdominal area, thigh, or deltoid, rotating sites within the same region 3

Higher Starting Doses for Severe Hyperglycemia

• For patients with A1C ≥9%, blood glucose ≥300-350 mg/dL, or symptomatic/catabolic features: consider 0.3-0.5 units/kg/day as total daily dose using basal-bolus therapy immediately 1, 2
• This severe presentation warrants both basal AND prandial insulin from the outset, not basal alone 2

Type 1 Diabetes Starting Dose

• Approximately one-third of total daily insulin requirements as basal insulin 3
• Use short-acting premeal insulin for the remaining two-thirds 3

Foundation Therapy: Continue Metformin

Metformin must be continued when starting basal insulin unless contraindicated—this combination reduces insulin requirements, limits weight gain, and improves outcomes compared to insulin alone. 1, 2

• Maximum effective metformin dose: 2000-2500 mg daily 2
• Consider discontinuing sulfonylureas to reduce hypoglycemia risk, but keep metformin 1

Titration Algorithm

Standard Titration Schedule

Increase basal insulin by 2-4 units every 3 days until fasting glucose reaches 80-130 mg/dL: 1, 2, 4

• If fasting glucose 140-179 mg/dL: increase by 2 units every 3 days 2
• If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days 2
• If hypoglycemia occurs without clear cause: reduce dose by 10-20% immediately 1, 2

Patient Self-Titration

• Instruct patients in self-titration based on daily fasting glucose monitoring—this improves glycemic control 1, 5
• A simple rule: increase by 1 unit per day OR 2-4 units once or twice weekly until fasting glucose consistently reaches target 5

Critical Threshold: When to Stop Escalating Basal Insulin

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, STOP escalating and add prandial insulin or a GLP-1 receptor agonist instead. 1, 2, 4

Clinical Signals of "Overbasalization"

• Basal dose >0.5 units/kg/day 2, 4
• Bedtime-to-morning glucose differential ≥50 mg/dL 2, 4
• Hypoglycemia episodes 2, 4
• High glucose variability throughout the day 2, 4

Adding Prandial Insulin

• Start with 4 units of rapid-acting insulin before the largest meal OR 10% of current basal dose 1, 2
• Titrate prandial insulin by 1-2 units every 3 days based on 2-hour postprandial glucose 1, 2

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1, 2
• Check A1C every 3 months during active titration 2
• Reassess therapy every 3-6 months once stable 2

Common Pitfalls to Avoid

Do NOT Delay Insulin Initiation

Delaying insulin in patients not achieving glycemic goals with oral medications prolongs hyperglycemia exposure and increases complication risk. 1, 2

Do NOT Continue Escalating Basal Insulin Beyond 0.5-1.0 units/kg/day

Continuing to increase basal insulin beyond this threshold without adding prandial coverage leads to overbasalization—increased hypoglycemia risk with suboptimal control. 1, 2, 5

Do NOT Discontinue Metformin

Never stop metformin when starting insulin unless contraindicated—this leads to higher insulin requirements and more weight gain. 1, 2

Do NOT Use Sliding Scale Insulin as Monotherapy

Sliding scale insulin alone is explicitly condemned by all major guidelines—it treats hyperglycemia reactively rather than preventing it. 2

Special Populations

Elderly or High-Risk Patients

• Use lower starting doses: 0.1-0.25 units/kg/day for patients >65 years, those with renal failure, or poor oral intake 2

Hospitalized Patients

• For those on high-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% upon admission 2

Renal Impairment

• CKD Stage 5 with type 2 diabetes: reduce total daily insulin by 50% 2
• CKD Stage 5 with type 1 diabetes: reduce total daily insulin by 35-40% 2

Patient Education Essentials

• Proper injection technique and site rotation 2
• Recognition and treatment of hypoglycemia (15 grams fast-acting carbohydrate for glucose ≤70 mg/dL) 2
• Self-monitoring of blood glucose 1
• "Sick day" management rules 2
• Insulin storage and handling 2