Which one of the following statements regarding insulin hormone is correct?

Insulin is a peptide (protein) hormone produced endogenously by the human body [5]. Specifically, it is synthesized and secreted by the beta cells of the pancreatic islets of Langerhans [3]. Chemically, insulin is a 51-amino acid hormone consisting of two polypeptide chains linked by disulfide bonds [5]. Its primary physiological role is to regulate blood glucose levels by promoting the uptake of glucose into tissues such as the liver, fat, and skeletal muscle [6]. Unlike steroid hormones, which are derived from cholesterol and are lipophilic, insulin is a protein-based hormone [5]. While exogenous insulin (produced via recombinant DNA technology) is administered to patients with diabetes, the hormone itself is naturally produced within the human body to maintain glucose homeostasis [6]. Therefore, statement 4 is correct as it accurately identifies insulin's chemical nature as a protein hormone and its origin within the human body.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > Do You Know? > p. 111
2. [5] https://www.ncbi.nlm.nih.gov/sites/books/NBK541112/
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > Do You Know? > p. 110
4. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC1204764/
5. [6] https://www.nature.com/articles/s41392-022-01073-0