Objective The minimal model is used to estimate insulin sensitivity in patientswith diabetes, following an intravenous glucose tolerance test (IVGTT). Issueshave been reported regarding parameter estimation, including correlationbetween insulin sensitivity and action parameters. The objective was to reducethese issues, by modifying the input of glucose in the test.Methods Data were available for 24 volunteers following an IVGTT and glucoseclamp test. Correlation between parameters was explored using likelihood heat-maps. An integrated glucose –insulin model was used to simulate glucose andinsulin concentrations following new glucose inputs. The improved input for thetest was selected by ﬁnding the minimum inverse of the determinant of the Fisherinformation matrix.Key ﬁndings When the minimal model was ﬁtted to the IVGTT data, there wasclear correlation between the insulin parameters. With the glucose clamp, allparameters were correlated and badly estimated. The modiﬁed input, a bolusdose followed by constant infusion, resulted in improvement in parameter esti-mation and reduction in parameter correlation.Conclusions It is possible to reduce the issues with parameter estimation in theminimal model by modifying the glucose input, leading to a simpliﬁed test deignand a reduction in the total amount of glucose infused.