This study will be conducted as a single-center, open-label, 2-period, single-sequence, drug-drug interaction study to assess the effects of multiple dose LX4211 (400 mg administered as 2 × 200-mg tablets qd × 12 days) on the PK of single-dose digoxin (2 × 0.25-mg tablets) in healthy male and female subjects.

Inclusion Criteria:

• Adult subjects ≥18 to ≤55 years of age
• Vital signs at Screening in the following ranges: systolic blood pressure, 90-140 mmHg; diastolic blood pressure, 50-90 mmHg; heart rate, 45-100 bpm
• Body mass index (BMI) ≥18 and ≤32 kg/sq m
• Willing and able to provide written informed consent

Exclusion Criteria:

• Presence of clinically significant physical, laboratory, or ECG findings that, in the opinion of the Investigator and/or Sponsor, may interfere with any aspect of study conduct or interpretation of results
• History of clinically significant arrhythmias
• History of cardiac arrhythmias or palpitations associated with presyncope, syncope, or a family history of sudden cardiac death
• Use of any medications or supplements/supratherapeutic doses of vitamins within 14 days prior to the first dose administration and throughout the duration of the study
• Receipt of any investigational agent or study drug within 30 days prior to Screening
• Receipt of any protein- or antibody-based therapeutic agents within 3 months prior to Screening
• Prior exposure to LX4211
• Use of tobacco, smoking cessation products, or products containing nicotine within 3 months prior to Screening and for the duration of the study
• History of any serious adverse reaction or hypersensitivity to any inactive component of LX4211 or digoxin
• Existence of any surgical or medical condition that might interfere with the absorption, distribution, metabolism, or excretion of LX4211 or digoxin
• History of any major surgery within 6 months or anticipated surgery prior to Day 1
• History of any clinically significant hypoglycemia or hyperglycemia
• History of renal disease, or significantly abnormal kidney function test at Screening
• History of hepatic disease, or significantly abnormal liver function tests at Screening
• History of any clinically relevant psychiatric, renal, hepatic, pancreatic, endocrine, cardiovascular, neurological, hematological, or GI abnormality
• History of any active infection within 14 days prior to Day 1
• History of alcohol or substance abuse within 2 years prior to Screening
• Positive hepatitis panel
• Donation or loss of >500 mL of blood or blood product within 3 months prior to Screening
• Women who are breastfeeding or are planning to become pregnant during the study, or women who have a positive serum pregnancy test
• Positive urine glucose at Screening
• Positive urine screen for drugs of abuse and cotinine at Screening, Day -1, or Day 13
• Inability or difficulty swallowing whole tablets
• Unable or unwilling to cooperate with the Investigator for any reason