The US Food and Drug Administration issued a warning on Friday saying that use of a class of widely prescribed medications for type 2 diabetes is associated with severe joint pain in some patients.

The FDA said in a statement that it has came across nearly 33 cases of severe joint pain in patients that were taking a class of drugs known as DPP-4 inhibitors between Oct. 16, 2006, when the first one was approved, through Dec. 31, 2013.

It also found that the most frequent number of cases of occurred with Januvia, known generically as sitagliptin. Nearly 28 cases came across that were linked to Januvia.

Five cases were reported with AstraZeneca Plc's Onglyza (saxagliptin), two with Boehringer Ingelheim's Tradjenta (linagliptin), and one with Takeda Pharmaceutical's Nesina (alogliptin), shows FDA report.

A spokesman for Merck, Steven Cragle said, “Merck takes all safety information seriously and we worked closely with the FDA on this request. We are confident in the safety profile of sitagliptin”.

Boehringer Ingelheim spokeswoman Emily Geary said clinical trials of Tradjenta do not show any imbalance between linagliptin and placebo in musculoskeletal and connective tissue disorders or, more specifically, in joint disorders.

Furthermore, a spokesman for AstraZeneca, Andrew Davis, said the company specifically works with health authorities and scientific experts to help ensure patients and physicians have a clear understanding of the risk benefit profile of our medications.

The FDA said that in 20 of the cases the DPP-4 inhibitor was suspected as a cause of the pain and was discontinued within a month after the start of symptoms.

In remaining eight, a period of 44 days to a year elapsed between the onset of symptoms and discontinuation of the drug, said FDA.