Dose Range Finding Study of MK-0941 in Patients With Type 2 Diabetes Mellitus on Insulin (MK-0941-007 AM3 EXT1 AM1)(TERMINATED)

Inclusion Criteria: * has type 2 diabetes mellitus * has body mass index \>20 and \<43 kg/m\^2 * is a male, or a female who is unlikely to conceive * currently on a stable dose of insulin with or without metformin for Type 2 diabetes mellitus Extension Study Inclusion Criteria: * completed the base study either on double-blind study medication or as part of the post-treatment follow up population * had ≥85% compliance with double-blind and open-label medication during the base study double-blind treatment period Exclusion Criteria: * has any history of Type 1 diabetes mellitus or ketoacidosis * has received more that 1 week of thiazolidinedione (such as pioglitazone or rosiglitazone) therapy or injectable increatin-based therapy (such as Byetta) within the prior 8 weeks * has had ≥2 episodes during their lifetime or \>1 episode within the past year resulting in hypoglycemic seizures, comas, or unconsciousness * is on a weight loss program and is not in the maintenance phase, or patient is taking a weight loss medication (e.g., orlistat, sibutramine, rimonabant) within 8 weeks of Visit 1 * has undergone surgery within 30 days prior to Visit 1 or has planned major surgery