What is the appropriate treatment for a patient diagnosed with type 1 or type 2 diabetes?

Treatment Approach for Type 1 and Type 2 Diabetes

Insulin therapy is the cornerstone treatment for type 1 diabetes, while metformin is the first-line foundation therapy for most adults with type 2 diabetes, with treatment decisions guided by patient characteristics, comorbidities, and risk factors. 1, 2

Distinguishing Between Type 1 and Type 2 Diabetes

Accurate diagnosis is critical as treatment approaches differ significantly between diabetes types:

Diagnostic Features of Type 1 Diabetes:

• Autoimmune destruction of beta cells
• Age <35 years (though can occur at any age)
• Normal or low BMI (<25 kg/m²)
• Presence of weight loss
• Ketoacidosis at presentation
• Marked hyperglycemia
• Family history of autoimmunity
• Low C-peptide levels (<600 pmol/L or <1.8 ng/mL)
• Positive islet autoantibodies (though 5-10% may be antibody negative)
• Rapid progression to insulin dependence 1

Diagnostic Features of Type 2 Diabetes:

• Increased BMI (≥25 kg/m²)
• Absence of weight loss
• Absence of ketoacidosis
• Less marked hyperglycemia
• Non-White ethnicity (higher risk)
• Features of metabolic syndrome
• Older age (more common)
• Family history of type 2 diabetes
• Preserved C-peptide levels (>600 pmol/L or >1.8 ng/mL) 1

Treatment for Type 1 Diabetes

Initial Therapy:

• Insulin therapy is mandatory and should be initiated immediately upon diagnosis 1
• Starting total daily insulin dose: 0.4-1.0 units/kg of body weight (typically 0.5 units/kg if metabolically stable)
• Higher doses may be needed for patients presenting with diabetic ketoacidosis or during puberty 1

Insulin Regimen:

• Most patients should be treated with multiple daily injections (MDI) of both prandial and basal insulin or with continuous subcutaneous insulin infusion (CSII) 1
• Use rapid-acting insulin analogs to reduce hypoglycemia risk 1
• Education on matching prandial insulin doses to carbohydrate intake, premeal glucose levels, and anticipated physical activity 1

Glycemic Targets:

• General HbA1c target: <7% for most patients
• More stringent targets (<6.5%) for selected individuals with short duration of diabetes, long life expectancy, no significant cardiovascular disease
• Less stringent targets (<8%) for those with history of severe hypoglycemia, limited life expectancy, advanced complications, or extensive comorbidities 1

Treatment for Type 2 Diabetes

Initial Therapy:

• Metformin is the first-line foundation therapy for most adults with type 2 diabetes, along with lifestyle modifications 1, 2
• Early insulin therapy should be considered if:
  • Evidence of ongoing catabolism (weight loss)
  • Symptoms of hyperglycemia are present
  • Very high A1C levels (>10% [86 mmol/mol])
  • Blood glucose levels >300 mg/dL (16.7 mmol/L) 1

Progression of Therapy:

• If glycemic targets are not met with metformin monotherapy after 3-6 months, add a second agent based on patient factors 1
• For patients with established cardiovascular disease or high CV risk, add a GLP-1 receptor agonist or SGLT-2 inhibitor with proven cardiovascular benefit 2
• For patients with heart failure or chronic kidney disease, SGLT-2 inhibitors are preferred 2
• If insulin is needed, combination with a GLP-1 receptor agonist is recommended for greater efficacy 1

Special Considerations for Children/Adolescents with Type 2 Diabetes:

• If ketosis or ketoacidosis is present, start with insulin therapy until glycemia normalizes
• Metformin can be added after resolution of ketosis/ketoacidosis
• Initial treatment should include insulin when blood glucose ≥250 mg/dL (13.9 mmol/L) and/or A1C ≥8.5% 1

Lifestyle Management for All Diabetes Types

• Engage in at least 150 minutes of moderate-intensity aerobic activity weekly
• Perform 2-3 sessions of resistance exercise per week on non-consecutive days
• Focus on carbohydrates from vegetables, fruits, legumes, whole grains, and dairy products
• Limit sodium consumption to <2,300 mg/day
• For type 2 diabetes, aim for 7-10% weight loss if overweight or obese 2

Monitoring and Follow-up

• Monitor HbA1c at least twice yearly for stable patients, and quarterly for those not meeting glycemic targets or after therapy changes 1
• Regular monitoring of renal function, especially with SGLT-2 inhibitors and metformin 2
• Self-monitoring of blood glucose for patients on insulin or medications with hypoglycemia risk 2
• Comprehensive diabetes self-management education and support at diagnosis, annually, with changes in health status, and during transitions of care 2

Common Pitfalls to Avoid

1. Misdiagnosis: Misdiagnosis is common and can occur in 40% of adults with new type 1 diabetes (misdiagnosed as type 2). Use the AABBCC approach for better classification: Age, Autoimmunity, Body habitus, Background, Control, and Comorbidities 1

2. Delayed intensification: Treatment intensification for patients not meeting goals should not be delayed 1

3. Overbasalization with insulin: Watch for clinical signals such as basal dose >0.5 IU/kg/day, high bedtime-morning glucose differential, hypoglycemia, and high glycemic variability 1

4. Inadequate monitoring: For patients with possible type 1 diabetes not initially treated with insulin, careful monitoring and education are essential so insulin can be rapidly initiated if glycemic deterioration occurs 1

5. Neglecting cardiovascular risk management: Aggressively manage cardiovascular risk factors, including hypertension and dyslipidemia, especially in type 2 diabetes 2