Diabetes mellitus type 1 causes

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Case #1

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Causes

The exact cause of type 1 DM remains unknown. Studies have found that cause of Type 1 DM is the result of interactions of genetic, environmental, and immunologic factors:

Type 1 Diabetes causes
Genes associated with Type 1 DM	Genes important to type 1 diabetes pathogenesis Region Odds ratio Gene funtion PTPN22 1p13.2 1·89 Regulation of innate immune response, T-cell activation, and natural killer cell proliferation IL10 1q32.1 0·86 Cytokines and inflammatory response AFF3 2q11.2 1·11 Regulation of transcription IFIH1 2q24.2 0·85 0·85 0·59 Innate immune system NF-κB activation STAT4 2q32.3 1·10§ Cytokine-mediated signalling pathway CTLA4 2q33.2 0·82 0·84 T-cell activation CCR5 3p21.31 0·85 Th1 cell development and chemokine-mediated signalling pathway IL21, IL2 4q27 1·13 1·12 1·14 1·15 Cytokines and inflammatory response and Th1 or Th2 cell differentiation IL7R 5p13.2 1·11 T-cell-mediated cytotoxicity, immunoglobulin production, and antigen binding BACH2 6q15 1·10 0·88 1·20 Transcription TNFAIP3 6q23.3 1·12 Inflammatory response TAGAP 6q25.3 0·92 Signal transduction IKZF1 7p12.2 0·89 Immune-cell regulation GLIS3 9p24.2 1·12 1·12 0·90 Regulation of transcription IL2RA 10p15.1 1·20 0·73 0·52 0·62 0·82 Alternative mRNA splicing Th1 or Th2 cell differentiation PRKCQ 10p15.1 0·69 Apoptotic process, inflammatory response, innate immune response, and T-cell-receptor signalling pathway NRP1 10p11.22 1·11 Signal transduction INS 11p15.5 0·42 0·63 0·63 Insulin signalling pathway BAD 11q13.1 0·92 Apoptosis CD69 12p13.31 0·87 1·10 Signal transduction ITGB7 12q13.13 1·19 Response to virus and regulation of immune response ERBB3 12q13.2 1·25 Regulation of transcription, innate immune response, and lipid metabolism CYP27B1 12q14.1 0·82 Metabolism of lipids, lipoproteins, steroid hormones, and vitamin D SH2B3 12q24.12 1·24 0·76 0·76 Signal transduction GPR183 13q32.3 1·12 Humoral immune response DLK1 14q32.2 0·88 0·90 Regulation of gene expression RASGRP1 15q14 0·85 1·15 Inflammatory response to antigenic stimulus and cytokine production CTSH 15q25.1 0·81 0·78 0·90 Immune response-regulating signalling pathway T-cell-mediated cytotoxicity adaptive immune response CLEC16A 16p13.13 0·83 0·82 1·14 Unknown IL27 16p11.2 1·19 0·90 1·24 Inflammatory response and regulation of defence response to virus ORMDL3 17q12 0·90 Protein binding PTPN2 18p11.21 1·20 Cytokine signalling and B-cell and T-cell differentiation CD226 18q22.2 1·13 Immunoregulation and adaptive immune system TYK2 19p13.2 0·82 0·87 0·67 Cytokine-mediated signalling pathway, intracellular signal transduction, and type I interferon signalling pathway FUT2 19q13.33 0·87 0·75 0·87 Metabolic pathways UBASH3A 21q22.3 1·16 Regulation of cytokine production Regulation of T-cell receptor signalling pathway C1QTNF6 22q12.3 1·11 B-cell receptor signalling pathway, chemokine signalling pathway, and natural killer cell-mediated cytotoxicity
Envirnomental triggers associated with Type 1DM	Congenital rubella Maternal entero-viral infection Cesarean section Higher birth weight Older maternal age Low maternal intake of vegetables Enteroviral infection Frequent respiratory or enteric infections Abnormal microbiome Early exposure to cereals, root vegetables, eggs and cow's milk Infant weight gain Serious life events Persistent or recurrent entero-viral infections Overweight or increased height velocity High glycemic load, fructose intake Dietary nitrates or nitrosamines Puberty Steroid treatment Insulin resistance Psychological stress
Immunologic factors associated with Type 1 DM	Islet cell autoantibodies Activated lymphocytes in the islets, peripancreatic lymph nodes, and systemic circulation T lymphocytes that proliferate when stimulated with islet proteins Release of cytokines within the insulitis

The exact cause is unknown, but most likely there is a viral or environmental trigger in genetically susceptible people that causes an immune reaction. The body's white blood cells mistakenly attack the insulin-producing pancreatic beta cells. There are several forms of diabetes. Type 1 diabetes is called juvenile or insulin-dependent diabetes. Type 1 diabetes can occur at any age, but it is most often diagnosed in children, adolescents, or young adults.

Insulin is a hormone produced by special cells, called beta cells, in the pancreas. Insulin is needed to move blood sugar (glucose) into cells, where it is stored and later used for energy. In type 1 diabetes, these cells produce little or no insulin. Without enough insulin, glucose builds up in the bloodstream instead of going into the cells. The body is unable to use this glucose for energy. This leads to the symptoms of type 1 diabetes. Within 5 - 10 years, the insulin-producing beta cells of the pancreas are completely destroyed and the body can no longer produce insulin.