The results showed that the NAFLD patients with normal ALT value possess a tightly relationship with diabetes (OR = 2.30, 95% CI: 1.38–3.82; P <  0.01), hypertension (OR = 2.03, 95% CI: 1.47–2.80; P <  0.56) and metabolic syndrome (OR = 1.42, 95% CI: 1.00–2.00; P = 0.60). This evidence concerns the gene GPT and diabetes mellitus.