Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia secondary to increased insulin resistance, inadequate production of insulin to meet metabolic demand, increased hepatic glucose production, and atypical fat metabolism. In T2DM, insulin resistance may be rooted in genetics and obesity. Initially, insulin secretion increases to compensate for worsening insulin resistance. But over time, increased insulin production cannot compensate for insulin resistance.

Patients may initially present with symptoms of hyperglycemia such as blurred vision, vulvovaginitis, pruritus, and peripheral neuropathy, as well as recurrent yeast infections. If insulin deficiency is more severe, fatigue / weakness, polyuria, polydipsia, and sometimes weight loss may present as symptoms. Diabetic ketoacidosis is rare. Some patients are relatively asymptomatic until chronic complications of diabetes develop. Prior to the initial diagnosis, all patients develop impaired glucose tolerance or impaired fasting glucose.

T2DM is commonly associated with obesity, including childhood obesity, increased waist circumference, cardiovascular disease, end-stage renal disease, adult blindness, and nontraumatic lower extremity amputations, among other problems. Onset in youth is associated with a progressive increase in risk of complications over time, including microvascular complications. T2DM of more than 10 years' duration may increase the risk of dementia.

T2DM has a strong genetic component and tends to disproportionately affect older populations, individuals with a high body mass index (BMI), and individuals of African, Hispanic, American Indian, and Asian descent.

A large review of US Department of Veterans Affairs patient records suggests that individuals infected with SARS-CoV-2 were at greater risk of developing T2DM within a year, even those with mild or asymptomatic infection, although risk increased with severity of illness.

Related topics: bullosis diabeticorum, diabetes mellitus type 1, diabetic dermopathy, diabetic hyperosmolar syndrome, diabetic nephropathy, diabetic neuropathy, diabetic retinopathy, maturity-onset diabetes of the young (MODY), neurogenic ulcer