Type 2 diabetes (T2D) is a multifactorial metabolic disease in which hyperglycemia coexists with insulin resistance, β-cell dysfunction, dyslipidemia, and progressive microvascular and macrovascular complications. The structural versatility of the benzothiazole scaffold has enabled the development of a diverse array of preclinical compounds capable of modulating multiple diabetes-relevant targets. This review critically analyzes the available evidence on benzothiazole-derived compounds exhibiting antidiabetic or other diabetes-related pharmacological activities. No lower publication-date limit was imposed, and the literature included in the review ranged from 1997 to March 2026, encompassing in silico, in vitro, ex vivo, and in vivo evidence. The compounds are discussed according to their primary molecular targets, including α-glucosidase and α-amylase, dipeptidyl peptidase-4 (DPP-4), peroxisome proliferator-activated receptor -γ (PPAR-γ), protein tyrosine phosphatase 1B (PTP1B), glycogen phosphorylase, 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), aldose reductase, AMPK, and other emerging metabolic targets. Structure–activity relationships (SAR) are highlighted, demonstrating that C-2 functionalization, substitution at the C-5 and C-6 positions, halogenation, the presence of electron-donating or electron-withdrawing groups, and hybridization with thiazolidinedione, rhodanine, triazole, oxadiazole, and other pharmacophores can markedly alter potency, selectivity, and metabolic effects. Various derivatives have matched or outperformed reference agents such as acarbose, glibenclamide, pioglitazone, or aldose reductase inhibitors in preclinical assays. However, a direct comparison between studies is limited by the heterogeneity of models, endpoints, units, and dosing regimens, and clinical efficacy for T2D has not yet been established for this chemical class. Overall, the benzothiazole scaffold emerges not as a universal antidiabetic pharmacophore, but as a highly adaptable platform for the rational design of multitarget compounds.