Statistical analysis
diabetic
The sample size was calculated to detect with 90% power a prespecified increase of lactate of 20% from preprocedural levels, with a "one-side" probability of alpha error of 0.025. Sample size calculation was based on data from our historical cohort of diabetic patients taking metformin scheduled for coronary angiography, presenting a mean value of lactate before coronary angiography of 1.2 ± 0.7 mmol/l. A total of 150 patients was planned to be enrolled assuming dropout and attrition rate of 20% and 5%, respectively.Continuous variables were reported as mean ± standard deviation or median and interquartile range (IQR) and compared with Student’s t test or Mann–Whitney or Wilcoxon tests on the basis of normality of data, verified by Shapiro–Wilk test. Categorical variables are reported as N (%) and were compared with χ