By William Elliott, MD, FACP, and James Chan, PharmD, PhD

Dr. Elliott is Assistant Clinical Professor of Medicine, University of California, San Francisco.
Dr. Chan is Associate Clinical Professor, School of Pharmacy, University of California, San Francisco.

The FDA has approved the first biosimilar and interchangeable insulin. The agency approved insulin glargine-yfgn as a biosimilar to insulin glargine (Lantus) in June 2020. Now, the manufacturer has provided additional data to meet the criteria for interchangeability. Insulin glargine-yfgn is distributed as Semglee.


Insulin glargine-yfgn can be prescribed to improve glycemic control in pediatric and adult patients with type 1 diabetes mellitus and in adult patients with type 2 diabetes.1


The dose is individualized based on blood glucose monitoring, type of diabetes, metabolic needs, prior insulin use, and glycemic control.1 The drug can be administered one time per day at the same time every day into the deltoid, thigh, or abdomen. Rotate injection sites to lower the risk of localized cutaneous amyloidosis and lipodystrophy. The starting dose in type 1 diabetes patients should be about one-third of total daily insulin requirement. To satisfy the remainder of the daily insulin requirement, use short-acting premeal insulin.1 For patients with type 2 diabetes who are insulin-naïve, start at 0.2 units/kg or up to 10 units one time per day.1 Insulin glargine-yfgn is available as 3 mL single patient use prefilled pens and 100 units/mL in 10 mL multiple-dose vials.


Insulin glargine-yfgn is a cheaper version of Lantus. As an interchangeable biosimilar, it may be substituted at the pharmacy for the reference product without the need for the healthcare provider to intervene, similar to an FDA-approved generic drug.2


There are no known clinical disadvantages.


Biosimilar products labeled interchangeable can produce similar clinical results as the reference product. In terms of diminished efficacy or safety of switching between the product and the reference, the risk is not higher than the risk of using the reference product without switching or alternation.3

The labeling for insulin glargine-yfgn essentially is identical to Lantus, per FDA guidance.3 It incorporates the same clinical data that supported the agency’s finding of effectiveness and safety of the reference product. The FDA requires switching study or studies to demonstrate interchangeability.4 The agency recommends not including a description of data from clinical studies conducted to support a demonstration of interchangeability on interchangeable biosimilar labels.3


Insulin glargine-yfgn represents the first biosimilar to be granted interchangeable status and marks an important step for the FDA in supporting a competitive marketplace for biologics. It will be available at a significantly lower cost than Lantus ($98.65 for a 10 mL vial of U-100) vs. $283.56. For five 3 mL pens, the cost is $147.98 vs. $425.31. 


  1. Mylan Specialty LP. Semglee prescribing information. July 2021.
  2. U.S. Food & Drug Administration. Interchangeable biological products.
  3. U.S. Food & Drug Administration. Biosimilarity and interchangeability: Additional draft Q&As on biosimilar development and the BPCI Act. November 2020.
  4. U.S. Food & Drug Administration. Considerations in demonstrating interchangeability with a reference product guidance for industry. May 2019.