Background: The model-based dynamic insulin sensitivity and secretion test (DISST) uses fasting glucose (G0) as the basal glucose (GB) concentration when assessing insulin sensitivity (SI). However, this model was developed in a healthy, normoglycaemic cohort. We sought to determine the suitability the DISST model has for individuals with established type 2 diabetes (T2D). Methods: 14 participants with established T2D were recruited to take part in a dietary intervention study. Insulin-modified intravenous glucose tolerance tests (IM-IVGTT) were undertaken at week 0, 12 and 24 and were used with DISST model to identify GB. A total of 36 tests were conducted across 12 participants throughout the study. Measured G0 and identified GB values were compared using a Kolmogorov-Smirnov (KS) and signed rank (RS) test for the cohort. Results: There were significant differences between the G0 and identified GB values in this cohort (prs and pks < 0.0001), although both values were well correlated (R = 0.70). The residual plot demonstrates that the modified model captures the behaviour of the participants more accurately than the original model. Conclusions: This analysis has shown that GB is an important variable for modelling the glycaemic behaviour in T2D. These findings suggest that the original DISST model, while appropriate for normoglycaemic cohorts, needs to model basal glucose level as a variable for assessing individuals with established T2D.