DexCom (DXCM) is facing organic issues and a competition threat despite "doing everything" to overcome multiple challenges, Oppenheimer said in a Monday note.

The performance of the company's G7-10D glucose monitoring system is facing patients' concerns due to poor accuracy, failed sensor insertions, abrupt stoppages, and other issues, the analysts said.

Oppenheimer analysts also said competition "remains stiff," and that Abbott Laboratories' (ABT) glucose-ketone dual analyte sensor and L3 pump integrations "complicate" DXCM's T1D gains.

Referring to the over-the-counter continuous glucose monitor segment, the analysts said it is a "less appealing" segment due to higher price elasticity of demand and lack of predictability of new patient adds, the analysts said.

Oppenheimer downgraded DexCom to perform from outperform and removed its $102 price target.

Shares of the company were down 2% in recent Monday trading.

Price: 78.90, Change: -1.61, Percent Change: -2.00