San Diego-based Dexcom, a medical device developer, announced yesterday that it has filed for an IPO. Dexcom is looking to raise up to $70M for its implantable glucose sensors for diabetes. The company's sensors are intended for long term use for continuous monitoring of glucose levels. DexCom is backed by Canaan Partners, Federated Kaufman Fund, Fog City Fund, Invesco, RWI Group, St. Paul Venture Capital, Warburg Pincus, and Windamere Venture Partners. The company is pre-revenue and lost $17M in 2004.