The ratio between gamma-glutamyl transferase (GGT) and high-density lipoprotein cholesterol (HDL-c) shares a positive and nonlinear relationship with incident diabetes, reports a recent Japan study.

Researchers conducted a retrospective cohort analysis of 15,171 patients (mean age 43.69 years, 53.75 percent men), in whom GGT/HDL-c ratio was determined through a blood test after overnight fasting. Incident diabetes was defined as plasma glucose ≥7 mmol/L, glycated haemoglobin ≥6.5%, or self-reported diagnoses.

Over a median follow-up of s64.9 months, 350 patients developed diabetes, yielding an incidence rate of 3.77 per 1,000 person-years.

Multivariate analysis, fully adjusted for potential confounders, showed that each additional unit of GGT/HDL-c ratio led to a 1.3-percent increase in the risk of incident diabetes (hazard ratio [HR], 1.013, 95 percent confidence interval [CI], 1.002–1.024).

Applying a penalized spline method to Cox proportional hazards regression model, the researchers also found that diabetes risk shared a nonlinear relationship with log-transformed GGT/HDL-c ratio, with an inflection point at ratio value 6.477.

HR estimates were 2.568 (95 percent CI, 1.157–5.699) and 1.012 (95 percent CI, 1.001–1.023) on the left and right sides of the inflection point, respectively.

“When the GGT/HDL-c ratio is lower than 6.477, there is a significant positive association with the risk of diabetes. The result is expected to provide a reference for the clinical control of the GGT/HDL-c ratio,” the researchers said.

“When the GGT/HDL-c ratio level is below the inflection point, lowering the GGT/HDL-c ratio level can significantly reduce the risk of developing diabetes in the future,” they added.