July 29, 2008

Metabasis’ Results From Its Phase 2a Clinical Trial for MB07803 to Be Presented at the World Congress on Controversies to Consensus in Diabetes, Obesity and Hypertension

Metabasis Therapeutics (Nasdaq: MBRX) announced today that an oral presentation summarizing the results from the Company's Phase 2a clinical trial for MB07803 will be given at the World Congress on Controversies to Consensus in Diabetes, Obesity and Hypertension (CODHy), to be held in Barcelona, Spain, October 30 to November 2, 2008. MB07803 is the Company's second-generation fructose-1,6-bisphosphatase (FBPase) inhibitor for the treatment of type 2 diabetes.

As reported in April, Metabasis successfully completed a Phase 2a, 28-day initial proof-of-concept clinical trial for MB07803, its second-generation FBPase inhibitor product candidate for the treatment of type 2 diabetes. The primary efficacy endpoint of the clinical trial was achieved with administration of MB07803 once daily, resulting in a statistically and clinically significant reduction in fasting plasma glucose (FPG) at day 28 versus placebo (p=0.0177). The clinical trial also showed that MB07803 was safe and well tolerated. The overall adverse event profile was similar to that of placebo. Fasting lactate levels were within the normal range, and no patients experienced hyperlacticemia (a sustained lactate elevation above 4.5 mM).

Alan J. Garber, M.D., Ph.D., will give the presentation, entitled, "Phase 2a Efficacy, Safety and Tolerability Study of MB07803, A Second-Generation Fructose-1,6-Bisphosphatase Inhibitor, in Patients with Type 2 Diabetes Mellitus (T2DM)." Dr. Garber serves as Professor in the Departments of Medicine, Biochemistry and Molecular Biology, and Molecular Cellular Biology, at Baylor College of Medicine in Houston, Texas. He also serves as an Attending Physician at the Methodist Hospital and Ben Taub General Hospital, both in Houston, Texas. Dr. Garber was the Chair of the Council on Complications for the American Diabetes Association and chairman of numerous task forces and consensus development committees related to the field of diabetes and its complications. He has authored approximately 200 peer-reviewed publications, as well as book chapters and monographs on diabetes, its complications and related disorders. He has been intimately involved in clinical research throughout his career, notably with metformin and more recently with vildagliptin.

"The results of this Phase 2a clinical trial are very encouraging, and support the continued development of MB07803 as an important new therapy for treating type 2 diabetes," commented Dr. Howard Foyt, M.D., Ph.D., FACP, vice president of clinical development. "CODHy provides an excellent opportunity to present these results to the scientific community. We are pleased to have an individual of Dr. Alan Garber's stature presenting these data. Dr. Garber, who was a principal investigator on this clinical trial, is a leader in diabetes clinical research and is well recognized for his clinical trial work on metformin, as well as other diabetes drugs and for his specialized knowledge and experience in the areas of metabolic disease and diabetes. With respect to next steps for MB07803, based on the excellent safety profile observed in the successful Phase 2a trial, we are planning to evaluate higher doses in patients later this year with the aim of using the results of this trial to select doses for the Phase 2b clinical trial that we expect will begin in 2009."

About Type 2 Diabetes:

Diabetes is a rapidly growing, worldwide health crisis. According to the International Diabetes Federation, in 2007, the number of patients suffering with diabetes worldwide reached over 245 million, with treatment and prevention costs reaching approximately $232 billion. Approximately 90% of patients with diabetes worldwide have type 2 diabetes. According to the American Diabetes Association, diabetes is the fastest growing disease in the U.S. In 2007, approximately 20 million Americans, or 7% of the U.S. population, were afflicted with diabetes, with costs associated with the disease reaching $174 billion.

About Metabasis (www.mbasis.com):

Metabasis is a biopharmaceutical company using its proprietary technologies, scientific expertise and unique capabilities for targeting the liver and liver pathways. The Company has established a broad pipeline of product candidates and advanced research programs targeting large markets with significant unmet needs. Metabasis' core area of focus is on the discovery and development of drug candidates to treat metabolic diseases such as hyperlipidemia and diabetes, among others. Although not a core focus of the Company, Metabasis has also discovered and developed drug candidates indicated for the treatment of liver diseases such as hepatitis and primary liver cancer, which it now intends to license or partner. All product candidates were developed internally using proprietary technologies.

Forward-looking Statements:

Statements in this press release that are not strictly historical in nature constitute "forward-looking statements." Such statements include, but are not limited to, references to the Phase 2a clinical trial results of MB07803 and the continued development of MB07803, including the initiation of future clinical trials. Such forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause Metabasis' actual results to be materially different from historical results or from any results expressed or implied by such forward-looking statements. These factors include, but are not limited to, risks and uncertainties related to the progress and timing of clinical trials for Metabasis' product candidates; the fact that positive results from preclinical studies and early clinical trials does not necessarily mean later clinical trials will succeed; difficulties or delays in development, testing, obtaining regulatory approval, producing and marketing Metabasis' product candidates; serious adverse side effects or inadequate efficacy of, or serious adverse events related to, Metabasis' product candidates or proprietary technologies; the risk that Metabasis will not be able to build more value or retain rights for direct commercialization of its product candidates; Metabasis' dependence on its licensees and collaborators for the clinical development and registration of, as well as information relating to, certain of its product candidates; potential conflicts with collaborators that could delay or prevent the development or commercialization of Metabasis' product candidates; the scope and validity of intellectual property protection for Metabasis' product candidates, proprietary technologies and their uses; competition from other pharmaceutical or biotechnology companies; Metabasis' ability to obtain additional financing to support its operations; and other factors discussed in the "Risk Factors" section of Metabasis' Quarterly Report on Form 10-Q for the three months ended March 31, 2008 and in Metabasis' other filings with the Securities and Exchange Commission. All forward-looking statements are qualified in their entirety by this cautionary statement. Metabasis is providing this information as of the date of this release and does not undertake any obligation to update any forward-looking statements contained in this release as a result of new information, future events or otherwise.