NPPB and diabetes mellitus: GDF-15 levels were positively correlated with age (p = 0.037), diabetes (p = 0.036), and NT-proBNP levels (p = 0.013) in HER2-positive breast cancer patients and tended to be positively correlated with TC levels (p = 0.086) and TnT levels (p = 0.082), but the correlations were not statistically significant (Table 2).