In a diabetic patient taking only Basaglar (insulin glargine) 30 units daily with a hemoglobin A1c of 7.9%, should I prescribe metformin, empagliflozin (Jardiance), or both?

Add Both Metformin and Jardiance (Empagliflozin)

For a diabetic patient on Basaglar 30 units daily with an A1c of 7.9%, you should add both metformin AND empagliflozin (Jardiance) to the regimen. This patient is already on insulin monotherapy with suboptimal control, and current guidelines strongly support adding oral agents rather than simply increasing insulin doses.

Rationale for Dual Addition

Why Not Metformin Alone?

While metformin is the preferred first-line oral agent 1, 2, adding metformin alone to this patient's existing insulin regimen will likely be insufficient. The patient has an A1c of 7.9% on insulin alone, indicating they need more aggressive therapy. Metformin should be continued when used in combination with other agents, including insulin 3, but monotherapy addition typically reduces A1c by only 0.7-1.0% 4, 2.

Why Add Jardiance?

For patients with type 2 diabetes on insulin who are not at glycemic goal, adding an SGLT2 inhibitor with demonstrated cardiovascular benefit is recommended independent of A1c level 2, 5. Empagliflozin specifically:

• Reduces A1c by 0.6-0.9% when added to existing therapy 6
• Provides cardiovascular mortality reduction (38% reduction in CV death) 7
• Reduces systolic blood pressure by 2.6-4.8 mmHg 6
• Promotes weight loss of 2.5-2.8% 6
• Does not increase hypoglycemia risk when used without sulfonylureas 8

The Combination Approach

The 2021 ADA guidelines explicitly state that for patients with established ASCVD or high cardiovascular risk, an SGLT2 inhibitor with demonstrated cardiovascular benefit should be part of the glucose-lowering regimen independent of A1c 2. Even without documented cardiovascular disease, this patient's need for insulin therapy suggests longer diabetes duration and higher risk.

The combination of metformin + empagliflozin + insulin provides:

• Complementary mechanisms of action
• Superior A1c reduction (potentially 1.5-2.0% total reduction)
• Cardiovascular and renal protection
• Weight neutrality or loss (offsetting insulin-associated weight gain)
• Maintained insulin sensitivity

Practical Implementation

Starting Doses

• Metformin: Start 500mg once or twice daily with meals, titrate to 1000mg twice daily over 2-4 weeks to minimize GI side effects 1, 2
• Empagliflozin: Start 10mg once daily in the morning 6
• Basaglar: Continue current dose initially, but monitor closely

Insulin Adjustment Strategy

Anticipate needing to reduce Basaglar dose by 10-20% within 2-4 weeks to prevent hypoglycemia as the oral agents take effect. The SGLT2 inhibitor will begin working within days, while metformin's full effect takes 2-3 weeks.

Monitoring Requirements

• Check fasting glucose daily for first 2 weeks
• Recheck A1c in 3 months
• Monitor for genital mycotic infections (empagliflozin side effect)
• Check vitamin B12 annually on metformin 3
• Assess renal function before starting and periodically (empagliflozin requires eGFR >30 for initiation, though can continue if eGFR drops below this) 8, 7

Critical Contraindications to Check

For Metformin:

• eGFR <30 mL/min/1.73 m² (contraindicated) 1
• eGFR 30-45: Use with caution, may need dose reduction

For Empagliflozin:

• eGFR <20 mL/min/1.73 m² (do not initiate) 7, 6
• History of diabetic ketoacidosis
• Severe hepatic impairment

Why Not Metformin OR Jardiance Alone?

Sequential addition of single agents represents outdated therapeutic inertia. The 2020 VERIFY trial demonstrated that initial combination therapy is superior to sequential addition for maintaining glycemic control 4, 2. While that trial used DPP-4 inhibitors, the principle applies: this patient needs approximately 1.5-2.0% A1c reduction to reach goal, which requires combination therapy.

The 2021 KDIGO guidelines specifically recommend that SGLT2 inhibitors can be added to other antihyperglycemic medications when glycemic targets are not met 8, and the cardiovascular benefits are "out of proportion to HbA1c reductions, suggesting effects beyond glucose lowering" 8.

Common Pitfalls to Avoid

1. Don't delay adding oral agents because the patient is "already on insulin" - this represents therapeutic inertia 4, 2
2. Don't increase insulin dose alone - this increases hypoglycemia and weight gain risk without addressing cardiovascular protection
3. Don't forget to educate about volume depletion with empagliflozin, especially if patient takes diuretics 8
4. Don't stop metformin if GI side effects occur - try extended-release formulation or slower titration first 1

The evidence strongly supports adding both agents simultaneously rather than sequentially, providing faster achievement of glycemic goals with cardiovascular and renal protection.