What is the first line of treatment for a patient with Type 1 (T1DM) diabetes?

First-Line Treatment for Type 1 Diabetes

The first-line treatment for Type 1 diabetes is insulin therapy, specifically using multiple daily injections (MDI) of both basal and prandial insulin or continuous subcutaneous insulin infusion (CSII), with rapid-acting insulin analogues preferred over regular human insulin to minimize hypoglycemia risk. 1, 2, 3

Insulin Regimen Structure

Start with a total daily insulin dose of 0.5 units/kg body weight in metabolically stable patients, divided approximately 50% as basal insulin and 50% as prandial (mealtime) insulin. 1, 2, 3

• The acceptable range for total daily insulin is 0.4-1.0 units/kg, with higher doses needed during puberty (approaching 1.0 units/kg or more) or in patients presenting with diabetic ketoacidosis. 1, 3
• Basal insulin is administered once or twice daily to provide continuous background insulin coverage. 3
• Prandial insulin (rapid-acting) is administered before each meal to cover postprandial glucose excursions. 3

Insulin Type Selection

Use rapid-acting insulin analogues (aspart, lispro, or glulisine) for prandial coverage rather than regular human insulin, as they are associated with less hypoglycemia while achieving equivalent HbA1c reductions. 1, 2

• Rapid-acting and long-acting insulin analogues developed after the DCCT trial demonstrate less hypoglycemia compared to human insulins while matching HbA1c improvements. 1
• The DCCT demonstrated that intensive therapy with MDI or CSII improved glucose control and resulted in better long-term microvascular, macrovascular, and all-cause mortality outcomes. 1

Delivery Method Options

Choose between two equally effective intensive insulin delivery methods:

Multiple Daily Injections (MDI)

• Consists of basal insulin once or twice daily plus rapid-acting insulin before each meal. 3
• This is the most common starting approach for newly diagnosed patients. 1

Continuous Subcutaneous Insulin Infusion (CSII)

• Provides a small advantage over MDI with an HbA1c reduction of -0.30 percentage points (95% CI, -0.58 to -0.02) and reduced severe hypoglycemia rates. 1, 3
• Should be encouraged in patients with active patient and family participation, particularly when combined with continuous glucose monitoring (CGM). 1
• Automated insulin delivery systems should be considered for all adults with Type 1 diabetes to improve glycemic control. 2

Essential Patient Education Components

Educate all patients on matching prandial insulin doses to three key factors: 1, 2, 3

• Carbohydrate intake at each meal (carbohydrate counting is foundational). 1, 2
• Premeal blood glucose levels to determine correction doses. 1, 2
• Anticipated physical activity that may affect insulin requirements. 1, 2

Patients who master carbohydrate counting should advance to fat and protein gram estimation for more precise insulin dosing. 1, 2

Monitoring Requirements

• Continuous glucose monitoring should be considered for all patients, particularly those with hypoglycemia unawareness or frequent hypoglycemic episodes. 2
• HbA1c should be measured every 3 months to determine if glycemic targets have been achieved and maintained. 3
• Fasting plasma glucose values should be used to titrate basal insulin, while both fasting and postprandial glucose values guide mealtime insulin adjustments. 2

Hypoglycemia Prevention

Prescribe glucagon for all patients at increased risk of clinically significant hypoglycemia (glucose <54 mg/dL), with family members and caregivers educated on administration. 2, 3

• Glucagon preparations that do not require reconstitution are preferred for ease of emergency use. 2
• Glucose (15-20 g) is the preferred treatment for conscious individuals with hypoglycemia (glucose ≤70 mg/dL). 3

Common Pitfalls to Avoid

• Do not use NPH insulin as basal coverage in Type 1 diabetes due to its peak action, short duration, and high variability, which increase hypoglycemia risk. 4
• Do not use premixed insulin preparations as they lack the flexibility needed to address individual postprandial glucose control adequately. 4
• Do not abruptly discontinue any adjunctive oral medications when starting insulin therapy due to risk of rebound hyperglycemia. 5
• Avoid intramuscular injections, especially with long-acting insulins, as severe hypoglycemia may result. 5

Adjunctive Therapy Considerations

Pramlintide is the only FDA-approved adjunctive therapy for Type 1 diabetes, indicated for patients who have not achieved glycemic targets after optimizing insulin therapy. 1, 3, 6

• If pramlintide is used, reduce prandial insulin dosing to minimize severe hypoglycemia risk. 1, 3
• Other agents (metformin, GLP-1 receptor agonists, SGLT-2 inhibitors) remain investigational and are not FDA-approved for Type 1 diabetes. 1, 6