There were statistically significant differences in SpO2 (P = 0.003), smoking history (pack/year) (P = 0.002), CAT score (P = 0.000), FABP-4 level (P = 0.000), and IL-6 (P = 0.000) between the COPD groups based on GOLD grade. This evidence concerns the gene FABP4 and chronic obstructive pulmonary disease.