South Korea Study: Empagliflozin Beats Metformin for Blood Sugar Swings in New Diabetics

A study from South Korea has found that empagliflozin (brand name Jardiance) significantly outperformed metformin — the most commonly prescribed first-line diabetes drug in the United States — in reducing dangerous blood sugar fluctuations among people newly diagnosed with type 2 diabetes. The findings, published in the Journal of Diabetes and Its Complications (2026), add important international evidence to an ongoing debate about whether metformin should remain the automatic first choice for newly diagnosed patients.

What the South Korean Researchers Did

Researchers at Seoul National University Bundang Hospital enrolled 46 adults with newly diagnosed type 2 diabetes — meaning none had ever taken diabetes medication before. Participants had A1C levels between 6.5% and 10.0%, roughly matching a mild-to-moderate diagnosis range familiar to US clinicians. Half received empagliflozin (10 mg/day) and half received metformin (1,000 mg/day) for 12 weeks. Crucially, all participants wore continuous glucose monitors (CGMs), allowing researchers to capture not just average blood sugar but how wildly it fluctuated throughout each day.

Why an International Perspective Matters Here

South Korea has one of the world's most rigorous diabetes research infrastructures, and Korean patients tend to have lower BMIs than American patients while still experiencing significant metabolic complications — making their findings a useful complement to US-based research that often focuses on higher-weight populations. This study helps answer whether empagliflozin's benefits extend across different metabolic profiles.

Key Findings — In Plain English

The primary measurement was something called MAGE — Mean Amplitude of Glucose Excursions — which tracks how dramatically blood sugar spikes and crashes throughout the day. Think of it as a "turbulence score" for your blood sugar.

• Empagliflozin reduced MAGE by 19.58 mg/dL
• Metformin reduced MAGE by only 4.33 mg/dL
• That's nearly a 5-times greater reduction in blood sugar swings

Empagliflozin also delivered greater A1C reductions (-1.15% vs. -0.78%), meaningful weight loss, smaller waist circumference, higher HDL ("good") cholesterol, and lower triglycerides and uric acid levels. Time-in-range — the percentage of hours blood sugar stayed between 70–180 mg/dL — improved in both groups with no significant difference between them.

How This Compares to US Guidelines

The American Diabetes Association's 2024 Standards of Care still list metformin as a preferred first-line agent for many newly diagnosed patients, though they now strongly recommend SGLT2 inhibitors like empagliflozin for patients with established cardiovascular disease or high cardiovascular risk. This South Korean study suggests the blood-sugar-stabilizing benefits of empagliflozin may warrant a broader conversation about its use even earlier — before cardiovascular risk becomes a factor.

Why This Matters for US Patients

Blood sugar variability — not just average blood sugar — is increasingly recognized as an independent risk factor for diabetic complications including nerve damage, kidney disease, and cardiovascular events. Many US patients who are newly diagnosed and prescribed metformin may be achieving acceptable A1C numbers while still experiencing significant daily blood sugar swings that a CGM would reveal. This study suggests empagliflozin may offer a smoother, more stable blood sugar profile from the very start of treatment. US patients should discuss with their endocrinologist or primary care provider whether empagliflozin might be appropriate as an initial therapy, particularly if CGM data shows high glucose variability. Insurance coverage and cost remain practical considerations in the US that do not apply equally in South Korea's healthcare system.

Study Citation

Lim, Park, & Jeong. "Empagliflozin versus metformin for glucose variability and metabolic outcomes in drug-naïve type 2 diabetes: The EMPA-FIT study." Journal of Diabetes and Its Complications, 2026. PMID: 41223492. DOI: 10.1016/j.jdiacomp.2025.109214. Institution: Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.