Glucagon-like peptide-1 (GLP-1) is a key metabolic hormone secreted by intestinal L-cells in response to nutrient ingestion. It plays a central role in regulating glucose homeostasis by enhancing insulin secretion, inhibiting glucagon release, delaying gastric emptying, and suppressing appetite. While glucose, fat, and protein are established stimulators of GLP-1 release, calcium has emerged as a key modulator of this enteroendocrine axis. Recent studies have shown that extracellular calcium, acting through the calcium-sensing receptor (CaSR) and voltage-gated calcium channels, triggers intracellular calcium influx, which is essential for GLP-1 exocytosis from L-cells. This highlights the role of calcium not merely as a dietary mineral but as a signaling ion that links nutrient sensing in the gastrointestinal tract to the hormonal regulation of blood glucose homeostasis. This chapter briefly explains how calcium influences the GLP-1-mediated gut-glucose axis.