Lexicon Announces a Publication in the American Diabetes Association's Journal, Diabetes Care

Results from Phase 2b Clinical Study in Patients with Type 2 Diabetes Provide
Evidence that SGLT1 inhibition with LX4211 Provides a Clinically Meaningful Benefit

The Woodlands, Texas, September 11, 2014 - Lexicon Pharmaceuticals, Inc. (Nasdaq: LXRX), announced a publication in the online edition of the American Diabetes Association's journal, Diabetes Care, entitled, "Greater Dose-Ranging Effects on A1C Levels Than on Glucosuria With LX4211, a Dual Inhibitor of Sodium Glucose Transporters SGLT1 and SGLT2, in Type 2 Diabetes on Metformin Monotherapy". The publication provided detailed results from the Phase 2b clinical study of LX4211 that Lexicon conducted in patients with type 2 diabetes. A complete copy of the publication can be found on Diabetes Care website at care.diabetesjournals.org.

"This peer-reviewed publication provides a detailed assessment of how, as dose escalated, LX4211 produced additional dose-dependent reductions in A1C in the absence of corresponding increases in urinary glucose excretion," said Dr. Brian Zambrowicz, Lexicon's executive vice president and chief scientific officer. "This provides further evidence that the SGLT1 inhibition by LX4211 produces a clinically meaningful benefit for patients with type 2 diabetes and further differentiates LX4211 as a first-in-class dual inhibitor of both SGLT1 and SGLT2."

In a double-blind, randomized, placebo-controlled, 12-week study in 299 patients with poorly controlled type 2 diabetes on metformin therapy, LX4211 provided a statistically significant reduction in A1C in a dose-dependent manner of 0.42% (75 mg once a day), 0.52% (200 mg once a day), 0.80% (200 mg twice a day), and 0.92% (400 mg once a day) as compared to a 0.09% reduction for placebo (p<0.001 for all doses). Greater A1C reductions were produced by the 400 mg once a day dose than the 200 mg once a day dose without higher urinary glucose excretion. In addition, LX4211 significantly reduced body weight by 1.85 kg (p<0.001) and systolic blood pressure by 5.7 mm Hg (p<0.001). Adverse events were generally mild to moderate and the overall incidence of adverse events with LX4211 was similar to placebo.

About Lexicon
Lexicon is a biopharmaceutical company focused on developing breakthrough treatments for human disease. Lexicon has clinical-stage drug programs for diabetes, carcinoid syndrome, and other indications, all of which were discovered by Lexicon's research team. Lexicon has used its proprietary gene knockout technology to identify more than 100 promising drug targets. For additional information about Lexicon and its programs, please visit www.lexpharma.com.

Safe Harbor Statement
This press release contains "forward-looking statements," including statements relating to Lexicon's clinical development of LX4211, characterizations of the results of and projected timing of clinical trials of LX4211, and the potential therapeutic and commercial potential of LX4211. The press release also contains forward-looking statements relating to Lexicon's growth and future operating results, discovery and development of products, strategic alliances and intellectual property, as well as other matters that are not historical facts or information. All forward-looking statements are based on management's current assumptions and expectations and involve risks, uncertainties and other important factors, specifically including those relating to Lexicon's ability to meet its capital requirements, successfully conduct clinical development of LX4211 and preclinical and clinical development of its other potential drug candidates, advance additional candidates into preclinical and clinical development, obtain necessary regulatory approvals, achieve its operational objectives, obtain patent protection for its discoveries and establish strategic alliances, as well as additional factors relating to manufacturing, intellectual property rights, and the therapeutic or commercial value of its drug candidates, that may cause Lexicon's actual results to be materially different from any future results expressed or implied by such forward-looking statements. Information identifying such important factors is contained under "Risk Factors" in Lexicon's annual report on Form 10-K for the year ended December 31, 2013, as filed with the Securities and Exchange Commission. Lexicon undertakes no obligation to update or revise any such forward-looking statements, whether as a result of new information, future events or otherwise.

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