Interaction between Sitagliptin and Chromium picolinate
Moderate Synergy

ID DDInter1679 and DDInter374
Interaction Pharmacologic dosages of chromium (200 mcg/day or more for adults) may help improve diabetic control and reduce the requirements for insulin and other antidiabetic agents. Chromium appears to play a role in normal insulin function and glucose utilization.
Management Until further data are available, therapy with pharmacologic dosages of chromium should be administered cautiously in patients receiving insulin or other antidiabetic agents. Patients should be monitored for changes in diabetic medication requirements.
References
Alternative for Sitagliptin A10B
Alternative for Chromium picolinate -

Potential Metabolism Interactions

Substrate-Substrate Interaction:If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction:Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction:Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.