What is the recommended insulin therapy for type 1 diabetes?

Insulin Therapy for Type 1 Diabetes

Most people with type 1 diabetes should be treated with multiple daily injections (MDI) of both basal and prandial insulin, or alternatively with continuous subcutaneous insulin infusion (CSII/pump therapy), using rapid-acting insulin analogs to minimize hypoglycemia risk. 1

Insulin Regimen Selection

Multiple Daily Injections (MDI) - First-Line Approach

• MDI consists of basal insulin (long-acting analog) once or twice daily PLUS rapid-acting insulin analog before each meal, which remains the standard approach for most patients with type 1 diabetes 1, 2
• Basal insulin options include insulin glargine (Lantus), insulin degludec, or NPH insulin, with long-acting analogs preferred due to lower hypoglycemia risk, particularly nocturnal episodes 1, 2
• Prandial insulin options include rapid-acting analogs (aspart, lispro, glulisine) or ultra-rapid-acting formulations (faster-acting aspart), which are superior to regular human insulin for postprandial glucose control and hypoglycemia reduction 1, 2

Continuous Subcutaneous Insulin Infusion (CSII/Pump Therapy)

• Consider CSII for patients not meeting glycemic targets with MDI, experiencing frequent or severe hypoglycemia, or with pronounced dawn phenomenon 2
• CSII provides modest but meaningful advantages: approximately 0.30% greater A1C reduction compared to MDI and reduced severe hypoglycemia rates 1
• Patients successfully using CSII should maintain access to this therapy even after age 65 years 1

Automated Insulin Delivery (AID) Systems - Emerging Standard

• Hybrid closed-loop systems (automated insulin delivery) are superior to sensor-augmented pump therapy alone, increasing time in range and reducing hypoglycemia 2
• The FDA has approved hybrid closed-loop systems that automatically adjust basal insulin delivery based on continuous glucose monitoring data 1
• Consider AID systems for patients capable of using the device safely, though cost and accessibility remain barriers 2

Initial Insulin Dosing

Starting Dose Calculation

• Begin with 0.4-1.0 units/kg/day of total daily insulin, with 0.5 units/kg/day typical for metabolically stable patients 1, 2
• Distribute approximately 30-50% as basal insulin and the remainder as prandial insulin 2
• Higher doses (up to 1.0 units/kg/day) are required during puberty or following presentation with diabetic ketoacidosis 1

Specific Basal Insulin Dosing (from FDA Label)

• When initiating insulin glargine in type 1 diabetes, use approximately one-third of total daily insulin requirements as basal insulin, with short-acting premeal insulin providing the remainder 3
• Administer basal insulin subcutaneously once daily at the same time each day into the abdominal area, thigh, or deltoid, rotating injection sites within the same region 3

Patient Education Requirements

Insulin Dose Adjustment Skills

• Educate all patients on matching prandial insulin doses to three factors: carbohydrate intake, premeal blood glucose levels, and anticipated physical activity 1, 2
• Patients who master carbohydrate counting should receive advanced education on fat and protein gram estimation for more precise dosing 1

Glucose Monitoring Integration

• Continuous glucose monitoring (CGM) is the standard of care for most people with type 1 diabetes, improving glycemic control regardless of insulin delivery method 2
• CGM with alerts/alarms helps identify and prevent hypoglycemic episodes, particularly important for those at high risk 2
• Increase frequency of blood glucose monitoring during any changes to insulin regimen 1, 3

Critical Safety Considerations

Hypoglycemia Prevention

• Rapid-acting insulin analogs reduce hypoglycemia risk compared to regular human insulin and should be used preferentially 1
• Newer long-acting basal analogs (U-300 glargine, degludec) confer lower hypoglycemia risk compared to U-100 glargine or NPH insulin 2
• The landmark DCCT trial demonstrated that intensive insulin therapy reduces microvascular complications by 50% and cardiovascular events by 57% in long-term follow-up, but increases severe hypoglycemia risk (62 vs 19 episodes per 100 patient-years) 1, 2

Injection Site Management

• Avoid injecting into areas of lipodystrophy or localized cutaneous amyloidosis, as this causes erratic insulin absorption and hyperglycemia 3
• When switching from lipodystrophic areas to normal tissue, closely monitor for hypoglycemia due to improved insulin absorption 3
• Rotate injection sites within the same anatomical region to prevent lipodystrophy 3

Common Pitfalls to Avoid

• Never dilute or mix insulin glargine with any other insulin or solution 3
• Do not administer basal insulin intravenously or via insulin pump (applies to glargine specifically) 3
• When switching from twice-daily NPH to once-daily long-acting analog, reduce total daily dose by 20% (use 80% of NPH dose) to prevent hypoglycemia 3

Glycemic Targets

• Target HbA1c <7% (53 mmol/mol) for most nonpregnant adults with type 1 diabetes to reduce long-term complications while balancing hypoglycemia risk 2
• More stringent targets (<6.5%) may be appropriate for selected individuals with short diabetes duration, long life expectancy, and no cardiovascular disease, if achievable without significant hypoglycemia 1
• Less stringent targets (<8%) are appropriate for patients with history of severe hypoglycemia, limited life expectancy, or advanced complications 1