Purpose of review This article provides an update on the role of the triglyceride to high-density lipoprotein-cholesterol (triglyceride/HDL-C) ratio in the setting of obesity-related insulin resistance and type 2 diabetes mellitus. Recent findings Insulin resistance and type 2 diabetes mellitus are well-established risk factors for cardiovascular diseases, and are commonly associated with metabolic abnormalities such as hypertriglyceridemia, low HDL-C and presence of small, dense low-dense lipoprotein (LDL) particles. Mounting evidence suggests that the triglyceride/HDL-C ratio is a marker of insulin resistance, although this relationship might vary as a function of ethnicity and sex. The triglyceride/HDL-C ratio has also been shown to correlate with other atherogenic lipid measurements, such as triglyceride-rich lipoproteins, remnant cholesterol and small dense LDL particles. Recent epidemiologic studies have shown that the triglyceride/HDL-C ratio associates with cardiovascular risk, mainly because of its association with insulin resistance. Finally, triglyceride/HDL-C can also be a marker of glycemic control, especially in obese patients with type 2 diabetes mellitus. Summary The triglyceride/HDL-C integrates information on triglyceride-rich lipoproteins, insulin resistance and glycemic control. Future studies may better define its specific clinical role.