Association of Triglyceride and Glucose (TyG) Index with Carotid Intimal Medical Thickness (IMT) in Apparently Health Subjects: The Chennai Urban Rural Epidemiology Study (CURES)

Insulin resistance has been associated with metabolic syndrome , diabetes and cardiovascular disorders. The triglyceride and glucose (TyG) index can be obtained easily by measuring blood glucose and serum triglyceride levels. It has also shown to be a useful surrogate to identify insulin resistance in healthy subjects. Carotid intimal medial thickness (IMT) is a marker, which is strongly associated with cardiovascular disease. This paper deals with the relationship between TyG index and carotid IMT in apparently healthy subjects.

Methods:

1719 apparently healthy nondiabetic subjects and 365 diabetic subjects were recruited from the Chennai Urban Rural Epidemiology Study, an ongoing epidemiological study in South India. The TyG index was calculated as the natural logarithm (Ln) of the product of plasma glucose and TG using the formula: Ln (TG [mg/dL] × glucose [mg/dL]/2). Carotid IMT was measured as per standard protocol. Statistical analysis was done using SPSS software version 20.0.

Results:

The mean TyG index was 4.5 in nondiabetic subjects. Statistically significant association was observed with age, waist and hip measurement, lipid parameters, HbA1c and carotid IMT (P < 0.001) in insulin resistant group. The homeostasis model assessment of insulin resistance (HOMA IR) index was well correlated with TyG index and was significantly higher in high TyG index group as compared to normal TyG index group (2.2 ± 1.3 vs 1.7 ± 1.2, p < 0.001). The mean carotid IMT was strongly associated with the tertiles of TyG index; 0.65 mm in first tertile, 0.69 mm in the second tertile and 0.72 mm in the third tertile, with a p value for trend of < 0.001. Mean TyG index and mean carotid IMT value was significantly higher in diabetic subjects compared to non-diabetic study subjects (5.0 vs 4.5- and 0.81-mm vs 0.69 mm with p value of < 0.001 for both).

Discussion/Conclusion:

This study shows that TyG index, a simple analytical tool of insulin resistance measurement can help to find out early atherosclerotic changes, even in a healthy individual, so that preventive strategies can be planned for a better cardiovascular outcome.