The word “diabetes” was from the Greek word meaning “a siphon” because people with diabetes “passed water like a siphon” whereas in Greek “mellitus” means “sweet like honey”, reflecting the sweet smell and taste of the patient’s urine due to the high level of glucose in it. Pancreatic beta (β) cells are destroyed by T cells of immune system, causing the start of type 1 diabetes mellitus, insulin-dependent diabetes mellitus, or juvenile-onset diabetes mellitus. The key objective of this paper is to clarify or impart, i.e., make known the real scientific truth about the fact that why and how the immune system specifically destroys insulin-producing β cells in the pancreas while exempting other adjacent hormone-producing cells including alpha (α ), delta (δ), and epsilon (ε) cells which secrete glucagon, somatostatin, and ghrelin hormones respectively. Type 1 diabetes mellitus is caused by occurrence of pathogenic mutation in the human genome found inside insulin-producing β cells. When a type 1 diabetes mellitus (T1DM) patient is treated by transplantation of pancreatic islets donated from a nondiabetic cadaver, there is a possibility or a challenge of graft rejection. The best optional method of treating T1DM patients, affected by pathogenic mutation, is applying the gene knock out and gene knock in method by identifying the gene or cluster of genes with interdependent functions affected & its/their function/s in the human genome’s sequence inside (β) cells of the patient. The scientific report of this study is one of the fruits of Genome Model which has massively and drastically revolutionized the whole world of both pure and applied biological sciences in favor of better life of all human races on this planet, Earth. Application of gene knock out and gene knock in method of treatment against T1DM is as possible as natural insertions of transposons (jumping genes) on DNA molecules. This is an exceptionally jubilant scientific victory for care provider health professionals and their clients (T1DM patients) including researcher scientists of biological sciences. The terms living-thing and nonliving-thing are replaced by genomic-thing and nongenomic-thing respectively in both pure & applied biological sciences. In other words, the terms living-thing and nonliving-thing are abolished/deleted from biological sciences because of their confusing, contradicting, groundless, illogical, unscientific, and misleading meanings in the interpretive active learning of student children and in the scientific analysis of researcher scientists of all human races of this planet. Textbooks of biological sciences that serve in schools as well as in universities being written with misleading terminologies of living-things & nonliving-things must be replaced by textbooks written with nonmisleading and very scientific terminologies of genomic-things & nongenomic-things without delay to safeguard the global quality of education. Devising in this way, we can make the present and coming generations of all human races far better proficient in biological sciences than ever before.