The exact causes of prediabetes, type 1 and type 2 diabetes are unknown, says Mayo Clinic. Although obesity is linked to the onset of type 2 diabetes, genetic and environmental factors are most strongly implicated. Gestational diabetes is caused by hormonal changes during pregnancy, not by diet. Early exposure to cow's milk or cow's milk formula, and eating cereals before the age of four months, are considered risk factors for type 1 diabetes, but do not directly cause it.
Risk factors for type 1 diabetes include environmental factors, the presence of autoantibodies, family history, lack of vitamin D and geography, according to Mayo Clinic. Age, weight, high blood pressure and genetics are risk factors for prediabetes and type 2 diabetes. Women who experience gestational diabetes during pregnancy and those with a condition called polycystic ovary syndrome have a greater risk of developing type 2 diabetes. Abnormal cholesterol and triglyceride levels increase the chances of type 2 diabetes. Risk factors for gestational diabetes include medical history, age, race and weight.
Blood sugar levels in the body are normally regulated by a hormone called insulin, notes Mayo Clinic. Type 1 diabetes occurs when the immune system destroys insulin-producing cells and allows sugar levels in the blood to rise. Prediabetes and type 2 diabetes develop when cells become resistant to the effects of insulin. During pregnancy, cells become more resistant to insulin, and if enough extra insulin isn't produced to compensate, gestational diabetes may result.