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

Insulin Initiation in Diabetes

For patients with type 2 diabetes requiring insulin, initiate basal insulin at 10 units per day or 0.1-0.2 units/kg/day depending on the degree of hyperglycemia, continuing metformin and possibly one additional non-insulin agent. 1, 2, 3

Type 1 vs Type 2 Diabetes: Different Starting Approaches

Type 1 Diabetes

• Start multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII) at diagnosis, with basal insulin comprising approximately one-third of total daily insulin requirements 4, 3, 5
• Short-acting or rapid-acting prandial insulin must be given with meals to satisfy the remainder of daily insulin requirements 3, 5

Type 2 Diabetes

• Basal insulin alone is the most convenient and appropriate initial regimen for most patients 1, 2, 4
• Consider insulin initiation when HbA1c ≥9% or blood glucose ≥300-350 mg/dL, and especially when HbA1c is 10-12% with symptomatic hyperglycemia 2, 4, 5
• For severe hyperglycemia with catabolic symptoms, consider starting both basal and mealtime insulin immediately 2

Specific Dosing Protocols

Initial Basal Insulin Dose

• Fixed dose: 10 units once daily 1, 2, 3
• Weight-based dose: 0.1-0.2 units/kg/day depending on severity of hyperglycemia 1, 2, 3
• Administer subcutaneously once daily at the same time each day (can be any time, but consistency is critical) 3
• Inject into abdominal area, thigh, or deltoid, rotating sites within the same region to prevent lipodystrophy 3

Titration Algorithm

• Equip patients with a self-titration algorithm based on fasting blood glucose monitoring 1, 2
• Increase basal insulin dose by 10-15% or 2-4 units once or twice weekly until fasting blood glucose target is achieved 4
• Titration should occur over days to weeks based on fasting glucose patterns 1

Medication Management During Insulin Initiation

Continue These Medications

• Continue metformin when initiating insulin (reduces weight gain, lowers insulin dose requirements, and decreases hypoglycemia) 2, 5
• Thiazolidinediones or SGLT2 inhibitors may be continued to improve glucose control and reduce total daily insulin dose 2

Discontinue These Medications

• Discontinue sulfonylureas, DPP-4 inhibitors, and GLP-1 receptor agonists when using complex insulin regimens beyond basal insulin alone 2, 4
• Do not abruptly discontinue oral medications due to risk of rebound hyperglycemia 5

When to Intensify Beyond Basal Insulin

Signs That Basal Insulin Alone Is Insufficient

• If basal insulin has been titrated to acceptable fasting glucose but HbA1c remains above target, advance to combination injectable therapy 4
• Options include adding a GLP-1 receptor agonist or adding 1-3 injections of rapid-acting insulin before meals 2
• Starting dose for mealtime insulin: 4 units, 0.1 units/kg, or 10% of the basal dose 2

Warning Signs of Overbasalization

• Basal dose >0.5 units/kg 4
• High bedtime-to-morning glucose differential 4
• Hypoglycemia or high glucose variability 4

Switching From Other Insulins to Basal Insulin

From NPH Insulin

• Once-daily NPH to once-daily basal insulin: use the same dose 3
• Twice-daily NPH to once-daily basal insulin: use 80% of total NPH dose 3

From Concentrated Insulin Glargine

• From TOUJEO (insulin glargine 300 units/mL) to insulin glargine 100 units/mL: use 80% of TOUJEO dose 3

Critical Patient Education Components

Essential Teaching Points

• Comprehensive education on self-monitoring of blood glucose, diet, and hypoglycemia recognition and treatment is critically important 1, 2
• Educate patients on the progressive nature of type 2 diabetes to avoid using insulin as a threat or describing it as personal failure 1, 2, 4
• For type 1 diabetes, teach patients how to match prandial insulin dose to carbohydrate intake, premeal blood glucose, and anticipated activity 4

Monitoring Requirements

• Increase frequency of blood glucose monitoring during insulin initiation and any regimen changes 3
• Use fasting plasma glucose values to titrate basal insulin 5
• Use both fasting and postprandial glucose values to titrate mealtime insulin 5

Common Pitfalls to Avoid

Clinical Errors

• Never delay insulin therapy in patients not achieving glycemic goals 2, 4
• Do not use insulin as a threat or punishment 1, 2
• Avoid inadequate patient education on self-monitoring, diet, and hypoglycemia management 2
• Watch for overbasalization (using higher than necessary doses of basal insulin) 1, 4

Administration Errors

• Do not administer basal insulin intravenously or via an insulin pump 3
• Do not dilute or mix insulin glargine with any other insulin or solution 3
• Do not inject into areas of lipodystrophy or localized cutaneous amyloidosis, as this causes erratic absorption 3
• Never share insulin pens, syringes, or needles between patients due to risk of blood-borne pathogen transmission 3

Special Considerations

Insulin Selection

• Long-acting basal analogs (glargine, detemir, or degludec) are preferred over NPH insulin 2
• Long-acting analogs reduce the risk of symptomatic and nocturnal hypoglycemia compared with NPH insulin 1, 6, 7

Cost Considerations

• Be aware of substantial price increases in insulin products over the past decade when selecting therapy 1

Hospital Setting

• For critically ill patients, target blood glucose as close to 110 mg/dL as possible and generally <140 mg/dL using intravenous insulin protocols 8
• For non-critically ill hospitalized patients, target fasting glucose <126 mg/dL and all random glucose <180-200 mg/dL 8
• Scheduled prandial insulin should be appropriately timed with meals; traditional sliding-scale insulin regimens as monotherapy are ineffective and not recommended 8