In diabetes type 1, your immune system normally fights harmful bacteria or viruses … attacks and destroys your insulin-producing cells in the pancreas. This leaves you with little or no insulin.
Instead of being transported into your cells, sugar builds up in your bloodstream. Type 1 diabets is thought by doctors to be caused by a combination of genetic susceptibility and environmental factors, though exactly what many of those factors are is still unclear.
Causes of prediabetes and type 2 diabete
Prediabetes can lead to type 2 diabetes and in type 2 diabetes, your cells become resistant to the action of insulin, and your pancreas is unable to make enough insulin to overcome this resistance.
Instead of moving into your cells where it’s needed for energy, insulin (sugar) builds up in your bloodstream. Exactly why this happens is uncertain, although as in type 1 diabetes, it’s believed that genetic and environmental factors play a role in the development of type 2. Being overweight is strongly linked to the development of type 2 diabetes, but not everyone with type 2 is overweight.
Causes of gestational diabetes
Medical doctors say that during pregnancy, the placenta produces hormones to sustain your pregnancy. These hormones make your cells more resistant to insulin. As your placenta grows larger in the second and third trimesters, it secretes more of these hormones making it even harder for insulin to do its job in your body.
Your pancreas responds by producing enough extra insulin to overcome this resistance. But sometimes your pancreas can not keep up. When this happens, too little glucose gets into your body cells and much of it stays in your blood.