What is OGIS

OGIS (an acronym for Oral Glucose Insulin Sensitivity) is a method for the assessment of insulin sensitivity from the oral glucose tolerance test. OGIS provides an index which is analogous to the index of insulin sensitivity obtained from the glucose clamp.

OGIS is explained in the paper: A. Mari, G. Pacini, E. Murphy, B. Ludvik and J.J. Nolan. A Model-Based Method for Assessing Insulin Sensitivity from the Oral Glucose Tolerance Test. Diabetes Care 24:539-548, 2001. Pdf here.

More information on the properties of OGIS, in comparison with other methods, can be found in: A. Mari, G. Pacini, A.R. Brazzale, B. Ahrén: Comparative evaluation of simple insulin sensitivity methods based on the oral glucose tolerance test. Diabetologia 48:748-751, 2005. Pdf here.

OGIS facts

• OGIS is an index of insulin sensitivity calculated from the oral glucose tolerance test (OGTT).
• OGIS is an estimate of the glucose clearance during a hyperinsulinemic euglycemic glucose clamp. Its units are ml/min per square meter of body surface area.
• OGIS has been validated against the hyperinsulinemic euglycemic glucose clamp by direct comparison of the glucose clearance values.
• OGIS can be calculated from a 2-hour or 3-hour OGTT.
• OGIS has been validated for a 75 g OGTT. Its use with other OGTT doses is possible, though not validated.
• OGIS requires glucose values at 0, 90, 120 min and insulin values at 0 and 90 min (2-h OGTT) or glucose values at 0, 120, 180 min and insulin values at 0 and 120 min (3-h OGTT).
• Data for OGIS can be both in common (mg/dl, μU/ml) and SI (mmol/l, pmol/l) units.
• OGIS reference values in various groups can be found in Table 3 of the original article (pdf here). Warning: the OGIS value depends on the insulin assay. The published reference values may not be appropriate for all assays.

OGIS calculators

OGIS can be calculated in three ways:

• Using a Microsoft Excel spreadsheet in which the formulas for OGIS have been implemented. This solution requires that the spreadsheet is completed by the user by filling all the necessary cells with the data and the OGIS formulas. Instructions for using the spreadsheets are contained in the Excel files.
• Using the web OGIS calculator. This solution is the quickest, but is suitable for the calculation of OGIS in a single subject only. To use this calculator, javascript must be enabled on your browser. Instructions for web OGIS are available at the calculator page.
• Using 1-2-3 OGIS, with which a template data file is downloaded, filled in with your data and submitted to the server to calculate OGIS. This solution requires only the data and the user doesn't have to care about the equations. Instructions for 1-2-3 OGIS can be found at the calculator page.

Choose from the menu above the calculation method that is most suitable for your needs.