Cardiovascular Effects of GLP-1 Receptor Activation

subcutaneous liraglutide daily

oral sitagliptin daily

Reduced calorie intake to achieve weight loss.

Subjects in the liraglutide arm will receive a placebo for sitagliptin. Those in the sitagliptin arm will receive a placebo for liraglutide. All subjects will receive a placebo for Exendin 9-39.

All subjects will receive Exendin (9-39) or matching placebo in crossover fashion during study days on the first and third days of the second week after randomization and again on the 5th and 7th days of the 14th week of treatment.