Introduction: The beneficial effects of resistant starch (RS) consumption on health in terms of reducing postprandial hyperglycaemia are evident. However, the potential of local Sarawak sago RS in regulating glucose has not been extensively studied. Objectives: This study aims to identify glucose-lowering effects of Sarawak sago RS, namely native (RS2) and chemically modified (RS4). Methodology: An oral glucose tolerance test (OGTT) was performed before and after 1 month treatment with sago RS2 and RS4 in spontaneously type 2 diabetes (T2D), Goto-Kakizaki (GK) rat. The mechanisms involved were further explored by screening the in vitro inhibitory activities of α-glucosidase and dipeptidyl peptidase (DPP)-IV. Histopathology examination for pancreas, kidney and liver tissues was done in response to sago RS intake using haematoxylin and eosin (H&E) staining. Results and discussion: The incremental area under the curve (iAUC) for blood glucose in RS-treated groups was decreased and significant in RS2-treated group (p