Type 2 Diabetes
From an endocrinology standpoint, type 2 diabetes is a progressive loss of insulin secretion layered on top of insulin resistance -- diagnosed by an A1c of 6.5% or higher, fasting glucose of 126 mg/dL or higher, or a 2-hour OGTT of 200 mg/dL or higher, per ADA Standards of Care in Diabetes-2026.
Symptoms
Increased thirst and urination, unexplained weight loss, fatigue, and blurred vision are classic, but many people are diagnosed on routine labs with no symptoms at all -- the pancreas typically loses a substantial share of its insulin-producing capacity before glucose rises high enough to cause symptoms.
Causes and risk
Genetics, visceral fat, inactivity, and age all drive the underlying insulin resistance; the disease becomes clinically apparent once beta-cell insulin output can no longer compensate for it.
How it is evaluated
Beyond A1c and fasting glucose, an endocrinology workup looks at the pattern over time, kidney function, and lipids, since diabetes management is inseparable from cardiovascular and renal risk.
Treatment
Metformin remains a common first-line agent, but the ADA 2026 guideline recommends a GLP-1 receptor agonist and/or SGLT2 inhibitor independent of A1c for anyone with cardiovascular disease, heart failure, or chronic kidney disease. Because beta-cell function continues to decline over time in most people, treatment plans are expected to intensify, not because of treatment failure but because of the disease’s own natural course.
When to seek care
Diabetic ketoacidosis (nausea, vomiting, abdominal pain, rapid breathing, confusion, fruity-smelling breath) and hyperosmolar hyperglycemic state are medical emergencies requiring immediate care.