A Study Designed to Determine the Safety and Pharmacological Response ofMKC253 Inhalation Powder in Adults With Type 2 Diabetes Mellitus

Inclusion Criteria: * Non-smoking males and females between 18 and 70 years of age * Body Mass Index (BMI) of \< 32 kg/m2 * Diabetes managed on a stable regimen of diet and exercise within the preceding 8 weeks and/or metformin and/or a sulfonylurea or meglitinide or alpha glucosidase inhibitors, without any dose adjustments within the preceding 8 weeks. For subjects taking both metformin and sulfonylurea or meglitinide or alpha glucosidase inhibitor, one or both oral agents must be less than 1/2 the maximal allowable dose as cited in the product label. * HbA1c = 6.2 to = 8.5%. Fasting C-peptide = 0.5 ng/mL. On the last 3 days of the washout period (Day -3, -2, and -1) subjects should have a FBG (finger stick) = 13.5 mmol/L. * Normal pulmonary function and performance on pulmonary function tests * Written Informed Consent * Treatment with any type of anti-diabetic therapy other than metformin, sulfonylurea, meglitinide and alpha glucosidase inhibitors within the preceding 12 weeks \[ie, thiazolidinediones (TZDs), dipeptyl peptidase inhibitors (DPP-IV), Symlin (pramlintide acetate) and or Byetta (exenatide)\]. Exclusion Criteria: * Exposure to any investigational medications or devices within the previous 90 days prior to trial entry or participation in another clinical trial while participating in this trial. * Use of any prescription medication within 90 days prior to screening, other than allowed anti-diabetic therapy, that has not been approved by the PI and Sponsor. The use of alpha blockers, antihypertensives, proton pump inhibitors and cholesterol medication as co-medications is allowed throughout the study. * Significant improvement in pre- to post-bronchodilator spirometry (defined as an increase of 12% AND 200 mL in either FVC OR FEV1). * Serum creatinine above Upper Limit of Normal (ULN) as defined by the laboratory * Any other condition which, in the opinion of the PI, makes the subject unsuitable for the clinical trial, or could limit the validity of the informed consent and/or impair the subject's ability to participate in the trial.