What are the recommended treatment regimens for type 1 and type 2 diabetes?

Recommended Treatment Regimens for Type 1 and Type 2 Diabetes

For type 1 diabetes, multiple daily insulin injections or continuous subcutaneous insulin infusion are the standard treatments, while type 2 diabetes requires a stepwise approach starting with metformin and progressing to combination therapy with SGLT-2 inhibitors or GLP-1 receptor agonists based on cardiovascular risk factors. 1, 2

Type 1 Diabetes Treatment

Insulin Therapy

• Initial insulin dosing: 0.4-1.0 units/kg/day of total insulin, with typical starting dose of 0.5 units/kg/day in metabolically stable patients 1
• Insulin regimen options:
  1. Multiple daily injections (MDI): 3-4 injections per day with basal and prandial insulin 1
  2. Continuous subcutaneous insulin infusion (CSII/insulin pump) 1
  3. Rapid-acting insulin analogs should be used to reduce hypoglycemia risk 1

Insulin Distribution

• Typically 50% as basal insulin and 50% as prandial insulin 1
• Prandial insulin should be matched to:
  • Carbohydrate intake
  • Pre-meal blood glucose levels
  • Anticipated physical activity 1

Monitoring

• Self-monitoring of blood glucose or continuous glucose monitoring (CGM) is essential 1
• CGM improves outcomes with both injected and infused insulin 1

Special Considerations

• Higher insulin doses may be required during puberty 1
• For patients with frequent nocturnal hypoglycemia or hypoglycemia unawareness, sensor-augmented low glucose threshold suspend pumps may be considered 1
• Patients who have been successfully using CSII should have continued access after age 65 1

Type 2 Diabetes Treatment

Initial Therapy

• Start with lifestyle modifications including:

  • Heart-healthy dietary pattern (Mediterranean, DASH, or vegetarian/vegan diet)
  • 150 minutes per week of moderate-intensity aerobic activity or 75 minutes of vigorous activity
  • Weight loss goal of ≥5% for overweight/obese patients 2

• Metformin should be initiated at or soon after diagnosis along with lifestyle therapy 1, 2

  • Benefits: improved glycemic control, weight neutrality or modest weight loss, reduced cardiovascular risk, low cost
  • Start with low dose and gradually increase to reduce gastrointestinal side effects
  • Use with caution in patients with renal impairment (eGFR < 45 mL/min/1.73m²) 2

Treatment Intensification Algorithm

When monotherapy with metformin at maximum tolerated dose does not achieve or maintain HbA1c target over 3 months:

1. For patients with established/high risk of atherosclerotic cardiovascular disease, heart failure, or chronic kidney disease:

   • Add an SGLT-2 inhibitor (strong recommendation) 1, 2
   • Benefits: reduces heart failure hospitalizations, slows CKD progression, provides cardiovascular risk reduction

2. For patients with increased stroke risk or when weight loss is an important goal:

   • Add a GLP-1 receptor agonist (strong recommendation) 1, 2
   • Benefits: reduces risk for all-cause mortality, major adverse cardiovascular events, stroke, and promotes weight loss

3. For patients with HbA1c ≥9%:

   • Consider initial dual-combination therapy to achieve glycemic control more quickly 1

4. For patients with HbA1c ≥10% or blood glucose ≥300 mg/dL:

   • Consider early introduction of insulin, especially if there is evidence of ongoing catabolism (weight loss) or symptoms of hyperglycemia 1

Insulin in Type 2 Diabetes

• If insulin is needed, continue metformin unless contraindicated 1
• A GLP-1 receptor agonist is preferred to insulin when possible 1
• If insulin is used, combination with a GLP-1 receptor agonist is recommended for greater efficacy, durability, and reduced weight gain and hypoglycemia 1

Monitoring and Follow-up for Both Types

• Reevaluate medication plan every 3-6 months and adjust as needed 2
• Assess glycemic response with HbA1c every 3-6 months 2
• Target HbA1c < 7% for most patients, but may be individualized based on hypoglycemia risk, disease duration, and comorbidities 1

Important Considerations and Pitfalls

Hypoglycemia Risk

• Hypoglycemia is the biggest obstacle for intensive insulin therapy
• Risk is particularly high with insulin and sulfonylureas 2
• Use insulin analogs when possible to reduce this risk 2

Medication Adjustments

• When adding an SGLT-2 inhibitor or GLP-1 agonist that results in adequate glycemic control, reduce or discontinue existing treatment with sulfonylureas or long-acting insulins to reduce hypoglycemia risk 2

Medication-Specific Concerns

• Monitor for vitamin B12 deficiency in patients on long-term metformin (>4 years) 2
• SGLT2 inhibitors have a rare risk of diabetic ketoacidosis and may increase risk of genital mycotic infections 2

The evidence clearly demonstrates that appropriate glycemic control reduces microvascular and macrovascular complications in both type 1 and type 2 diabetes. Treatment should be initiated promptly and intensified as needed to achieve target glycemic goals while minimizing the risk of hypoglycemia and other adverse effects.