Type 2 DM is characterized by insulin resistance, which may be combined with relatively reduced insulin secretion. The defective responsiveness of body tissues to insulin is believed to involve the insulin receptor. However, the specific defects are not known. Diabetes mellitus cases due to a known defect are classified separately. Type 2 DM is the most common type of diabetes mellitus.
Epigenetic phenomena, such as DNA methylation and histone modification, have also been implicated in the pathogenesis of hypertension. For example, a high-salt diet appears to unmask nephron development caused by methylation. Maternal water deprivation and protein restriction during pregnancy increase renin-angiotensin expression in the fetus. Mental stress induces a DNA methylase, which enhances autonomic responsiveness. The pattern of serine protease inhibitor gene methylation predicts preeclampsia in pregnant women. 
According to the Mayo Clinic, doctors may use other tests to diagnose diabetes. For example, they may conduct a fasting blood glucose test, which is a blood glucose test done after a night of fasting. While a fasting blood sugar level of less than 100 milligrams per deciliter (mg/dL) is normal, one that is between 100 to 125 mg/dL signals prediabetes, and a reading that reaches 126 mg/dL on two separate occasions means you have diabetes.