This report describes Drosophila models of insulin-dependent diabetes mellitus (see MIM:222100) using "genetic ablation" techniques. The Drosophila insulin-like peptide genes (Ilp1 through Ilp8) are expressed in small clusters of cells, insulin-producing cells (IPCs), in the brain. The IPCs appear to be functionally analogous to the human pancreatic islet beta cells. In initial experiments, ablation of the IPC cells in larvae was achieved by targeted expression of the pro-apoptotic gene reaper (rpr). Ablation of these insulin-producing cells causes developmental delay, growth retardation, and elevated carbohydrate levels in larval hemolymph; in adults, increased fasting glucose levels in the hemolymph is observed, similar to that found in diabetic mammals.
IPC ablation initiated at the adult stage has also been investigated. Development of an oral glucose tolerance assay that can be used to test the response of adult flies has facilitated characterization of this system. IPC death can also be induced by increasing ER stress to the point that the unfolded protein response is activated, which triggers death of the IPCs by apoptosis.
[updated Mar. 2020 by FlyBase; FBrf0222196]
Type 1 diabetes occurs when the body's immune system attacks the insulin-producing beta cells in the pancreas and destroys them, resulting in the production of little or no insulin. (https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024702/)
The first signs and symptoms of the disorder are caused by high blood sugar (hyperglycemia) and may include frequent urination (polyuria), excessive thirst (polydipsia), fatigue, blurred vision, tingling or loss of feeling in the hands and feet, and weight loss. (Genetics Home Reference, type 1 diabetes; 2017.01.23)
Type 1 diabetes is usually diagnosed in children and young adults, although it can appear at any age. People with type 1 diabetes are dependent on supplied insulin. (https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes)
A first-degree relative of someone with type 1 diabetes has about a 6 in 100 chance of developing type 1 diabetes. This is higher than the chance of the general population, which is about 1 in 300. (http://patient.info/health/type-1-diabetes; 2017.01.23)
