Best Oral Medications for Type 2 Diabetes Mellitus

First-Line Therapy

The American College of Physicians recommends metformin as the first-line oral medication for most patients with type 2 diabetes mellitus due to its superior efficacy, favorable safety profile, and cost-effectiveness 1, 2
Metformin should be initiated when lifestyle modifications fail to adequately control hyperglycemia in patients with type 2 diabetes 1
Metformin offers additional benefits beyond glucose control, including weight neutrality or modest weight reduction 2, improved lipid profile (reduces LDL cholesterol and triglycerides) 3, lower risk of hypoglycemia compared to sulfonylureas 4, and lower all-cause and cardiovascular mortality compared to sulfonylureas 3
Metformin is cost-effective, available as a generic formulation 2

When metformin monotherapy fails to control hyperglycemia, a second agent should be added, with options including sulfonylureas, thiazolidinediones, DPP-4 inhibitors, SGLT-2 inhibitors, and GLP-1 receptor agonists 3, 5
All dual-therapy regimens reduce HbA1c by approximately an additional 1 percentage point compared to monotherapy 5
Sulfonylureas are the least expensive second-line option but have a higher risk of hypoglycemia and weight gain 5, 6, 7
Thiazolidinediones improve insulin sensitivity but can cause fluid retention and are contraindicated in heart failure 4

Individualize HbA1c targets based on patient's risk for complications, comorbidities, life expectancy, and preferences 3
An HbA1c target of less than 7% is reasonable for many but not all patients 3
Monitor for common side effects, including metformin's gastrointestinal effects (nausea, diarrhea, abdominal discomfort) 4, sulfonylureas' hypoglycemia 4, and thiazolidinediones' fluid retention, weight gain, and increased risk of heart failure 4

Start with lifestyle modifications (diet, exercise, weight loss) 1
If hyperglycemia persists, initiate metformin (unless contraindicated) 1
If glycemic targets are not achieved with metformin monotherapy, add a second agent based on patient-specific factors, considering cardiovascular disease, cost concerns, weight concerns, and heart failure 1, 3, 4, 5