From the Guidelines
The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) index is a simple clinical tool used to assess insulin resistance in patients, calculated using the formula: HOMA-IR = (Fasting glucose x Fasting insulin) / 22.5, as suggested by recent clinical practice guidelines 1. To calculate the HOMA-IR index:
- Measure fasting plasma glucose (in mmol/L) and fasting insulin levels (in μU/mL)
- Use the formula: HOMA-IR = (Fasting glucose x Fasting insulin) / 22.5 A HOMA-IR value can be used to estimate insulin resistance, with higher values indicating greater resistance. This index is useful for clinicians to quickly evaluate a patient's insulin sensitivity without requiring more complex or invasive tests, particularly in the context of metabolic dysfunction-associated steatotic liver disease (MASLD) 1. While HOMA-IR is widely used due to its simplicity, it's essential to note that it provides an estimate rather than a direct measurement of insulin resistance, and its validity depends on the ability of insulin secretion to adapt to insulin resistance, as highlighted in previous guidelines 1. For more precise assessments, especially in research settings, other methods like the euglycemic clamp technique may be preferred. However, in real-life clinical practice, HOMA-IR remains a valuable tool for identifying individuals at risk for type 2 diabetes or metabolic syndrome, and for monitoring the progression of liver disease 1.
From the Research
Definition of HOMA-IR Index
- The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) index is a method used to assess insulin resistance, which plays a crucial role in the pathogenesis of type 2 diabetes mellitus 2.
- It is calculated using fasting glucose and insulin serum concentrations 3.
Calculation and Reference Values
- The HOMA-IR index is calculated from fasting glucose and insulin serum concentrations, providing an estimate for insulin resistance 3.
- Reference values for HOMA-IR have been studied, with a reference value of 1.77 +/- 0.44 (mean +/- SD) reported in healthy individuals without obesity 2.
- Cut-off values for HOMA-IR have been proposed, including 2.53,3.50, and 3.00 for non-obese, obese, and total individuals, respectively 2.
- However, the cut-off values for HOMA-IR differ for different races, ages, genders, diseases, and complications, making it challenging to determine specific cut-off values 4.
Clinical Significance
- The HOMA-IR index is a key index for the primary prevention of diabetes mellitus and is used in guidelines for screening high-risk groups 4.
- Insulin resistance, as assessed by HOMA-IR, is a major pathophysiological factor in the development and progression of type 2 diabetes mellitus 4.
- The HOMA-IR index has been used to study the relationship between shift work and insulin resistance, with results showing a significant positive association between increased values of HOMA-IR and shift workers 5.
Challenges and Limitations
- There is a high degree of variability in determining threshold levels of HOMA-IR for defining insulin resistance, with distribution varying according to demographic characteristics such as age, sex, and race 6.
- The choice of insulin assay can also affect the calculated HOMA-IR values, highlighting the need for assay-specific reference intervals 3.