Metabolic Score for Insulin Resistance

The Metabolic Score for Insulin Resistance (METS-IR) is a metabolic index designed to quantify peripheral insulin sensitivity in humans. It was first described by Bello-Chavolla et al. in 2018^[1][2] and developed by the Metabolic Research Disease Unit at the Instituto Nacional de Ciencias Médicas Salvador Zubirán.^[3] METS-IR was validated in the Mexican population against the euglycemic hyperinsulinemic clamp and the frequently-sampled intravenous glucose tolerance test.^[1] It offers a non-insulin-based alternative to traditional methods such as SPINA Carb, HOMA-IR, and QUICKI. METS-IR is currently validated for assessing cardiometabolic risk in Latino population.^[1]

Derivation and validation

METS-IR was generated using linear regression against the M value adjusted by lean body mass obtained from the glucose clamp technique in Mexican subjects with and without type 2 diabetes mellitus. It is estimated using fasting laboratory values including glucose (in mg/dL), triglycerides (mg/dL) and high-density lipoprotein cholesterol (HDL-C, in mg/dL) along with body-mass index (BMI). The index can be estimated using the following formula:^[4]

${\displaystyle METS-IR={\frac {\ln[2*Glucose(mg/dL)+Triglycerides(mg/dL)]*BMI(kg/m^{2})}{\ln[HDL-C(mg/dL)]}}}$

The index holds a significant correlation with the M-value adjusted by lean mass (ρ = −0.622) obtained from the euglycemic hyperinsulinaemic clamp study adjusted for age and gender as well as minimal model estimates of glucose sensitivity.^[5] In an open population cohort study in Mexican population, METS-IR was shown to predict incident type 2 diabetes mellitus and a value of METS-IR >50.0 suggested up to three-fold higher risk of developing type 2 diabetes after an average of three years.^[1] In a nation-wide population-based study of Chinese subjects, METS-IR was also shown to identify subjects with metabolic syndrome independent of adiposity.^[6] METS-IR also predicts visceral fat content, subcutaneous adipose tissue, fasting insulin levels and ectopic fat accumulation in liver and pancreas.^[1]

Comparison to other indexes

METS-IR was compared with other non-insulin-based methods for estimating insulin sensitivity, including the Triglyceride-Glucose index (TyG),^[7] the triglyceride to HDL-C ratio,^[8] and the TyG-BMI index,^[9] showing a higher correlation and area under the ROC curve.^[1] However, in a study of Chinese subjects, Yu et al. found that TyG and TG/HDL-C performed better, likely due to ethnic differences in body composition.^[10] Given the role of ethnicity in modifying the performance of insulin sensitivity fasting-based indexes, further evaluations in different populations are required to establish performance of non-insulin-based methods.^[11]

See also

• Insulin resistance
• Homeostatic model assessment
• SPINA-GBeta
• SPINA-GR
• Disposition index
• Quantitative insulin sensitivity check index
• Diabetes mellitus
• Diabetes management