Marinae macroalgae, with their rich diversity of bioactive compounds, have gained attention as potential sources of natural antidiabetic agents. This chapter provides a comprehensive analysis of preclinical studies exploring the antidiabetic properties of algae, focusing on their effectiveness across various animal models. Algal compounds, including polysaccharides, phenolics, and fatty acids, exhibit promising hypoglycemic effects by modulating glucose metabolism, enhancing insulin sensitivity, and reducing oxidative stress. Preclinical animal studies serve as crucial tools in understanding these mechanisms, using models such as diabetic rodents to replicate metabolic characteristics of human diabetes. This chapter examines the methodologies and approaches employed in these studies, including different dosages, modes of administration, and treatment durations. Key findings from the animal studies reported earlier highlight significant glucose-lowering effects of algal extracts, supporting the potential of algae-derived compounds as complementary antidiabetic agents. However, preclinical studies are not without limitations; challenges such as variability in algal composition, differences in animal metabolism, and issues in scaling up for clinical applications are addressed. The chapter concludes by discussing future directions in algal antidiabetic research, emphasizing the need for standardized extraction and testing protocols, and exploring the potential of algae as sustainable alternatives in diabetes management. The insights provided aim to bridge the gap between preclinical efficacy and clinical translation, fostering a better understanding of algae as a source of novel antidiabetic therapeutics.