Postprocedural peak values of CK-MB ( 2.70 4.30 vs. 6.29 8.03 ng/ml , p < 0.001 ) and troponin I ( 0.02 0.05 vs. 0.07 0.10 ng/ml , p = 0.001 ) were also significantly lower in the metformin group than in the control group .