Reduced Time Points to Calculate the Composite Index

Abstract

S ince the original publication of the composite (Matsuda) index for the measurement of insulin sensitivity from plasma glucose and insulin concentrations during the oral glucose tolerance test (OGTT) (1), this index has been widely used by investigators throughout the world. According to Scopus, more than 1,000 articles have cited the original article (1) during the last 10 years, and several modifications of this index have been published (2,3). Although the basic idea is to use the plasma insulin and glucose areas under the curve (AUCs), the actual time points at which plasma insulin and glucose levels are measured during the OGTT may be few and the time intervals may not be equal.In some studies, fewer time points, usually 0, 60, and 120 min or only 0 and 120 min, have been obtained during the OGTT. We show here that calculation of the composite index using these fewer time points agrees well with the original calculation, which was based on five plasma glucose and insulin measurements. Although it is difficult to imagine a reasonable AUC when samples from only 0 and 120 min are available, the simple index below works quite well. ISI(composite) ϭ k/sqrt͑G 0 ϫ I 0 ϫ G 120 ϫ I 120 )where ISI(composite) is the insulin sensitivity index, k (ϭ 10,000) is a constant that provides numbers that are easy to deal with, G 0 and G 120 represent the plasma glucose concentrations at times 0 and 120 min, I 0 and I 120 represent the plasma insulin concentrations at times 0 and 120 min, and sqrt is the mathematical function to calculate the square root. Thus, all of the calculations are based on the concept of the original publication.Using the data from the original publication (N ϭ 153) (1), correlation coefficients were calculated relating whole-body ISI(composite) to 1) the rate of insulinstimulated glucose disposal (R d ) during the euglycemic insulin clamp and 2) hepatic insulin sensitivity (His) measured with tritiated glucose: His ϭ 1,000/HGP ϫ FPI, where HGP is hepatic glucose production, the primary determinant of fasting plasma glucose level, and FPI is fasting plasma insulin. R d (or His) and an ISI(composite) calculated from 0, 30, 60, 90, and 120 min (set A); 0, 60, and 120 min (set B); and 0 and 120 min (set C) were significantly (P Ͻ 0.01) correlated with r ϭ 0.732 (r ϭ 0.670) in set A, r ϭ 0.741 (r ϭ 0.680) in set B, and r ϭ 0.772 (r ϭ 0.651) in set C.Although ISI(composite) calculated using different time points cannot be compared between different studies, within any given study the index provides a reasonable index of whole-body insulin sensitivity.

Post–Glucose Load Measures of Insulin Resistance and Prognosis of Nondiabetic Patients With Ischemic Stroke

“…G 0 and G 120 represent plasma glucose concentrations at times 0 and 120 minutes, and I 0 and I 120 represent insulin concentrations at times 0 and 120 minutes. Units for the ISI(composite) are mg×mU/dL×L 19. The Gutt ISI 0,120 was calculated as ISI 0,120 =m/[G×log 10 (I)], in which m=[75 000 mg+(fasting glucose−2‐hour glucose)×0.19×body weight kg]/120 minutes, G represents mean fasting and 2‐hour glucose concentrations, and I represents mean fasting and 2‐hour insulin concentrations.…”

Prediction of Glucose Metabolism Disorder Risk Using a Machine Learning Algorithm: Pilot Study (Preprint)

“…The HbA1c (Japan Diabetes Society; JDS) values were converted to National Glycohemoglobin Standardization Program (NGSP) values using the formula developed by the JDS (see below). [9] In addition, insulin sensitivity was calculated with the simple insulin sensitivity index, as follows: [10,11] (1) HbA1c = [HbA1c (JDS)(%)×1.02+0.25(%)] Diabetes is defined in accordance with the American Diabetes Association (ADA) guidelines [12] as an FPG level ≥126 mg/dL, a 2-hour plasma glucose level during a OGTT ≥200 mg/dL, or an HbA1c concentration ≥6.5%. Subjects with an FPG level <100 mg/dL, a 2-hour plasma glucose level during the OGTT <140 mg/dL, and an HbA1c level <5.7% are defined as having normal glucose tolerance.…”

Insulin Resistance can be Easily Estimated by Body Mass Index and Waist Circumference in a General Japanese Population

“…They were 50±9 years old and 1453 subjects (85%) were male. Plasma glucose and insulin were measured at 0 and 120 min during the 75-g OGTT, from which the Matsuda index 3) and HOMA-IR 2) were calculated. The current analyses were performed after dividing the population randomly into two groups; one group (n = 860) was used as the training data, for model derivation, and the other (n = 859) as the test data, for model validation.…”

“…We read with great interest the recent report by Oka and colleagues 1) , who successfully assessed the association of visceral and subcutaneous adipose tissue with insulin resistance in a Japanese population, using the homeostasis model for the assessment of insulin resistance (HOMA-IR) 2) and the Matsuda index 3) as indices of insulin resistance/sensitivity. Their detailed investigations also showed that body mass index (BMI) was not inferior in predicting insulin resistance to the area of visceral fat tissue evaluated by computed tomography.…”