Insulin in the human body is produced by:

The pancreatic beta cells, which are found in specialised cell clusters called the Islets of Langerhans, produce and secrete the peptide hormone insulin. The pancreas secretes digestive enzymes as an exocrine gland and releases hormones into the bloodstream as an endocrine gland. Insulin's main function is to control blood sugar levels by making it easier for the body's cells to absorb glucose for storage or energy.