The U.S. Food and Drug Administration has approved Kirsty (insulin aspart-xjhz) as the first and only interchangeable rapid-acting insulin biosimilar to NovoLog (insulin aspart), marking a significant advancement in diabetes care and potentially improving access to affordable insulin for millions of Americans. The approval was announced by Biocon Biologics Ltd on July 15, 2025.
Expanding Treatment Options for Diabetes Patients
Kirsty is indicated to improve glycemic control in adults and pediatric patients with diabetes mellitus and will be available as a single-patient-use prefilled pen for subcutaneous use and a multiple-dose vial for subcutaneous and intravenous use. The approval represents the second insulin aspart biosimilar to receive FDA clearance, following Merilog (insulin-aspart-szjj) approved in February 2025.
"The FDA approval of Kirsty, the first and only interchangeable biosimilar rapid-acting Insulin Aspart in the U.S., is a significant step forward in our efforts to make insulin more accessible and affordable," said Shreehas Tambe, CEO & Managing Director of Biocon Biologics Ltd. "It builds on the foundation we laid with Semglee, reinforcing our commitment to scientific excellence and patient-centric innovation."
Addressing Critical Access Challenges
The interchangeable designation carries particular significance for patient access and market dynamics. Unlike standard biosimilars, interchangeable products may be substituted for the reference product at the pharmacy without requiring a new prescription, depending on state laws. This capability is expected to streamline patient access and further drive competition in the insulin market.
The approval addresses a critical healthcare challenge, as there are 38.4 million people with diabetes in the United States, approximately 11.6 percent of the total population, with nearly a quarter of them being undiagnosed. An additional 97.6 million Americans have been identified as prediabetic. Over 8.4 million Americans depend on insulin therapy to manage their condition.
The high cost of insulin has created significant barriers to access. A JAMA study highlighted that 1 in 5 U.S. adults under 65 years with diabetes who use insulin rationed their supply due to cost, with nearly 71% of adults reporting insulin rationing for financial reasons being under 65 years, making them ineligible for out-of-pocket cost limits established by the Inflation Reduction Act.
Market Impact and Clinical Data
Sales of insulin aspart in the United States were approximately $1.9 billion in 2024, according to IQVIA data. The FDA approval of Kirsty was based on a comprehensive package of analytical, nonclinical and clinical data, which confirmed that Kirsty is highly similar to NovoLog. The data demonstrated that there were no clinically meaningful differences between Kirsty and NovoLog in terms of safety, efficacy, purity and potency.
Biocon Biologics' Growing Portfolio
The approval expands Biocon Biologics' biosimilar insulin portfolio, which also includes Semglee (insulin glargine-yfgn injection), the first approved interchangeable biosimilar. Kirsty has been available in Europe and Canada since 2022. Biocon Biologics is a global leader in biosimilars and insulin production, ranking among the top three global players for recombinant human insulin and insulin glargine, providing over 9.2 billion doses of insulin globally.
The company has achieved multiple industry firsts, including the first to receive approval of biosimilar trastuzumab in the United States (Ogivri), as well as Fulphila (bPegfilgrastim), and Semglee (bInsulin glargine). Globally serving over 5.8 million patients annually, Biocon Biologics maintains a comprehensive portfolio of in-market and in-development biosimilar products across multiple therapies, including eight in the United States and seven in Canada.
Safety Profile and Administration
Kirsty is contraindicated during episodes of hypoglycemia and in patients with hypersensitivity to insulin aspart products or any of the excipients. Similar to NovoLog, Kirsty can be administered subcutaneously into the abdomen, buttocks, thighs, or upper arms, typically within 5 to 10 minutes before a meal. The 10-mL vial can also be used for continuous subcutaneous infusion or intravenously.
Key warnings and precautions include the need for close medical supervision when changing insulin regimens, increased glucose monitoring frequency, and awareness of potential hypoglycemia, medication errors, hypersensitivity reactions, and hypokalemia. Common adverse effects may include injection site reactions, rash, lipodystrophy, weight gain, and swelling in the hands and feet.
The FDA's continued approval of additional insulin biosimilars, particularly interchangeable ones, underscores its commitment to fostering a competitive marketplace for insulin products and increasing access to safe, effective, and high-quality medications at potentially lower price points.
