What is the typical starting point for insulin dosing?

Typical Starting Points for Insulin Dosing

For patients with diabetes, the typical starting point for insulin dosing is 0.5 units/kg/day for type 1 diabetes and 10 units per day or 0.1-0.2 units/kg/day for insulin-naive patients with type 2 diabetes. 1, 2

Type 1 Diabetes Initial Dosing

• The typical starting dose for metabolically stable adults with type 1 diabetes is 0.5 units/kg/day, with approximately half administered as prandial insulin and half as basal insulin 1
• Higher doses (0.4-1.0 units/kg/day) may be required during puberty, pregnancy, and medical illness 1
• Lower starting doses (0.2-0.6 units/kg/day) may be appropriate for young children and those with continued endogenous insulin production (during the "honeymoon period") 1
• In general, patients with type 1 diabetes require approximately 30-50% of their daily insulin as basal and the remainder as prandial insulin 1

Type 2 Diabetes Initial Dosing

• For insulin-naive patients with type 2 diabetes, the recommended starting dosage is 10 units per day or 0.1-0.2 units/kg/day 1, 2
• When basal insulin is added to oral antihyperglycemic agents, long-acting basal analogs (U-100 glargine or detemir) can be used instead of NPH insulin 1
• Basal insulin is usually prescribed in conjunction with metformin and sometimes one additional noninsulin agent 1

Dosing in Special Situations

Hospital Setting

• For hospitalized patients receiving enteral or parenteral feedings who require insulin:
  • In the absence of previous insulin dosing, a reasonable starting point is 5 units of NPH/detemir insulin subcutaneously every 12 hours or 10 units of insulin glargine every 24 hours 1
  • For patients receiving continuous tube feedings, calculate the total daily nutritional component as 1 unit of insulin for every 10-15g carbohydrate per day 1

Insulin Switching

• When switching from once-daily NPH insulin to once-daily insulin glargine, the recommended starting insulin glargine dosage is the same as the dosage of NPH being discontinued 2
• When switching from twice-daily NPH insulin to once-daily insulin glargine, the recommended starting insulin glargine dosage is 80% of the total NPH dosage 2
• When switching from NPH to Mixtard insulin, use 80% of the NPH dose rather than converting on a 1:1 basis 3

Insulin Titration

• After initiating insulin therapy, dose titration is crucial to achieve glycemic targets 4
• For basal insulin, increase the dose by 2 units every 3 days if fasting blood glucose remains above target, in the absence of hypoglycemia 4
• A simple titration regimen can involve adjusting the daily insulin dose by:
  • 0-2 units if mean fasting plasma glucose is ≥5.6-<6.7 mmol/L (≥100-<120 mg/dL)
  • 2 units if ≥6.7-<7.8 mmol/L (≥120-<140 mg/dL)
  • 4 units if ≥7.8-<10.0 mmol/L (≥140-<180 mg/dL)
  • 6-8 units if ≥10 mmol/L (≥180 mg/dL) 4

Common Pitfalls and Considerations

• During changes to a patient's insulin regimen, increase the frequency of blood glucose monitoring to reduce the risk of hypoglycemia 2
• Hypoglycemia is the most commonly reported adverse effect, especially within the first four weeks after switching to insulin glargine 5
• Insulin glargine should not be mixed with any other insulin product 5
• The timing of insulin administration can affect glycemic control - blood glucose levels tend to rise around the time of injection of insulin glargine whether given at lunch-time, dinner-time, or bed-time 6
• For patients experiencing hypoglycemia despite titration of once-daily glargine, consider a twice-daily regimen 7
• Insulin doses may need adjustment with changes in physical activity, meal patterns, during acute illness, or changes in renal or hepatic function 2

By following these evidence-based starting points for insulin dosing and making appropriate adjustments based on blood glucose monitoring, clinicians can help patients achieve optimal glycemic control while minimizing the risk of hypoglycemia.