Home / Glossary / Type 2 diabetes mellitus
Conditions

Type 2 diabetes

Persistently high sugar due to insulin resistance and a relative lack of insulin

Type 2 diabetes — cells resistant to insulin

Type 2 diabetes is the most common form (more than 90% of all cases). Its cause is not so much a lack of insulin as insulin resistance: the cells respond poorly to insulin, and the pancreas compensates by producing more and more of it — until it becomes exhausted.

It develops over years and often runs latent, growing out of prediabetes. It is closely linked to visceral fat and metabolic syndrome.

Why it develops

At its root is a combination of insulin resistance, an excess of visceral fat, hereditary predisposition and lifestyle (physical inactivity, a surplus of calories and fast carbohydrates). A skin sign of pronounced insulin resistance is acanthosis nigricans.

Why it is dangerous

The main threat is cardiovascular complications (heart attack, stroke): it is these, not the blood sugar itself, that most often shorten life. The kidneys, nerves and the retina of the eye also suffer.

What actually helps

Weight loss of 5–10% noticeably improves blood sugar control; with significant weight loss at early stages remission is possible (the DiRECT study). Nutrition, regular activity and, when indicated, medications work.

Reference ranges

The diagnostic criteria are the same as for diabetes overall (ADA, 2026):

Fasting glucose≥ 7.0 mmol/L
HbA1c≥ 6.5%
Glucose 2 h after a load≥ 11.1 mmol/L
Important: The diagnosis is confirmed by a repeat test if there are no overt symptoms of hyperglycemia.

Calculate using this marker

Calculators where Type 2 diabetes mellitus is used directly:

Diabetes Risk Screening for hidden prediabetes and type 2 diabetes from labs and risk factors Open METS-IR (Insulin Resistance) A non-insulin index of insulin resistance Open Metabolic Syndrome IDF/NCEP criteria — waist circumference, blood pressure, glucose, and lipids Open

Frequently asked questions

Is type 2 diabetes reversible?

At early stages — yes: with weight loss (especially significant) some patients achieve remission, when blood sugar normalizes without sugar-lowering drugs. But the predisposition remains, so the lifestyle must be maintained.

How does type 2 differ from type 1?

In type 1 the immune system destroys the cells that produce insulin — there is almost none, and insulin from outside is needed. In type 2 insulin is present, but the cells are resistant to it; treatment starts with lifestyle and pills.

Related terms

Diabetes mellitus A chronic disorder of glucose metabolism: type 2 is linked to insulin resistance and sharply raises cardiovascular risk. Insulin resistance Reduced sensitivity of cells to insulin Prediabetes Sugar above normal but not yet diabetes — a reversible "yellow zone" Metabolic syndrome A cluster of cardiometabolic risk factors Visceral fat Fat around the internal organs Glycated hemoglobin HbA1c — an indicator of blood sugar over 3 months METS-IR (Metabolic Score for Insulin Resistance) A non-insulin index of insulin sensitivity Acanthosis nigricans Dark, velvety patches of skin — a marker of insulin resistance

Sources

  1. ADA. Standards of Care in Diabetes — 2026
  2. Lean MEJ et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT). Lancet, 2018
  3. MedlinePlus (NIH) — Type 2 Diabetes
info
This content is educational and does not replace consultation with a physician. Reference ranges may vary depending on the laboratory and method — rely on the ranges stated on your own test report.
← All glossary terms