Comparative Pharmacological and Pharmaceutical Perspectives on Antidiabetic Therapies in Humans, Dogs, and Cats

Background/Objectives: Diabetes mellitus (DM) is an increasingly prevalent endocrine disorder affecting humans and companion animals. Type 1 DM (T1DM) and type 2 DM (T2DM) are well characterized in humans, and canine DM most often resembles T1DM, marked by insulin dependence and β-cell destruction. Conversely, feline DM shares key features with human T2DM, including insulin resistance, obesity-related inflammation, and islet amyloidosis. This review provides a comprehensive comparative analysis of antidiabetic therapies in humans, dogs, and cats, focusing on three core areas: disease pathophysiology, pharmacological and delivery strategies, and translational implications. In human medicine, a wide array of insulin analogs, oral hypoglycemic agents, and incretin-based therapies, including glucagon-like peptide-1 receptor agonists (liraglutide) and sodium-glucose cotransporter-2 inhibitors (empagliflozin), are available. Veterinary treatments remain limited to species-adapted insulin formulations and off-label use of human drugs. Interspecies differences in gastrointestinal physiology, drug metabolism, and behavioral compliance influence therapeutic efficacy and pharmacokinetics. Recent innovations, such as microneedle patches for insulin delivery and continuous glucose monitoring systems, show promise in humans and animals. Companion animals with naturally occurring diabetes serve as valuable models for preclinical testing of novel delivery platforms and long-acting formulations under real-world settings. While these technologies show potential, challenges remain in regulatory approval and behavioral adaptation in animals. Conclusions: Future research should prioritize pharmacokinetic bridging studies, veterinary-specific formulation trials, and device validation in animal models. By highlighting shared and species-specific characteristics of DM pathogenesis and treatment, this review advocates a One Health approach toward optimized antidiabetic therapies that benefit human and veterinary medicine.