IP Law Daily, PATENT—Fed. Cir.: PTAB’s obviousness finding affirmed in blood glucose monitor dispute, (Aug 19, 2025)
Organizations Mentioned:DexCom | Dexcom, Inc. | Klarquist Sparkman, LLP
By Kevin M. Finson, J.D.
The PTAB’s decision that a patent covering blood glucose monitors was rendered obvious by the prior art was affirmed because the board properly relied upon expert testimony about how a person of ordinary skill in the art would understand the prior art reference.
A seller of implantable blood glucose monitors failed to show any error in a PTAB obviousness determination, the U.S. Court of Appeals for the Federal Circuit has held. The board’s decisions about the teachings of the prior art were supported by expert testimony (Dexcom, Inc. v. Stewart, No. 24-1291 (Fed. Cir. Aug. 19, 2025)).
DexCom, Inc. (DexCom) was the owner of U.S. Patent No. 10,792,193 (the ’193 patent) which related to an implantable glucose sensor used in the treatment of diabetes. Abbott Diabetes Care, Inc. (Abbott) petitioned for inter partes review on the ground of obviousness. The Patent Trial and Appeal Board (PTAB) instituted review and found that claims 1-3 and 11-13 were unpatentable as obvious. DexCom appealed. Abbott withdrew from the appeal and the Acting Director of the USPTO intervened to defend the PTAB decision.
Teachings of the prior art. DexCom argued that the Board misinterpreted a prior art reference as requiring a three-layer stack of electrode traces used in the sensor. The court found that DexCom misread the Board’s opinion; the Board did not read the prior art reference as requiring a stacked electrode arrangement but based on a figure which showed both stacked and non-stacked electrodes the prior art reference encompassed both arrangements. These findings were supported by expert testimony.
Prior art status. DexCom also argued that the figure at issue from the prior art reference, which was a patent application, should not have been considered prior art at all. DexCom alleged that only a substantially different hand-drawn version of the figure which was found in the application as filed was actually prior, and the published version relied upon by Abbott came later. The court found that DexCom had waived this issue by raising it in a preliminary response and then not actually addressing it in the response before the Board.
The Federal Circuit affirmed the decision of the Board.
The Case is No. 24-1291.
Judge: Wang, N.
Attorneys: John D. Vandenberg (Klarquist Sparkman, LLP) for Dexcom, Inc. Maureen Donovan, U.S. Patent and Trademark Office, for Coke Morgan Stewart.
Companies: Dexcom, Inc.
Cases: Patent FedCirNews USPTO