Type 2 diabetes
How insulin resistance in liver, muscle and fat and a gradual failure of the beta cells combine to raise blood glucose, often silently, and how years of hyperglycaemia damage small and large blood vessels.
By the end, you can
- Describe how insulin normally coordinates the liver, skeletal muscle and adipose tissue.
- Explain insulin resistance in each of these tissues, including the role of visceral fat and fatty acids.
- Explain why diabetes appears only when beta cells can no longer compensate, and why it tends to progress.
- Explain why ketoacidosis is uncommon in type 2 diabetes but a hyperosmolar state can occur.
- Relate chronic hyperglycaemia to microvascular and macrovascular complications.
- Recognise the diagnostic thresholds, classic appearances and tests of type 2 diabetes, and explain how each main drug class acts on its mechanism.
What it is
Type 2 diabetes is diabetes mellitus caused by insulin resistance (tissues respond less to insulin) together with progressive beta-cell dysfunction (the pancreas cannot release enough insulin to overcome the resistance). It accounts for about nine in ten cases of diabetes, and its risk rises with age, excess fat (especially around the abdominal organs), physical inactivity and family history.
Normal function
Insulin coordinates the liver, muscle and fat
Insulin from the beta cells of the drains into the , so the receives it first and at the highest concentration. After a meal, insulin tells the liver to stop releasing glucose and to store it as glycogen.
In skeletal muscle, the largest site of insulin-stimulated glucose uptake, insulin moves the transporter GLUT4 to the cell membrane and promotes glycogen storage. In adipose tissue, it promotes uptake of glucose and fat and strongly suppresses lipolysis, the breakdown of stored triglyceride into fatty acids.
Beta cells match their output to need. Glucose triggers an early burst of insulin within minutes (first-phase release), followed by sustained secretion. Gut hormones released by a meal (incretins, such as GLP-1) amplify the response, so glucose taken by mouth produces more insulin than the same glucose given into a vein.
Underlying change · Step 1 of 4
Liver, muscle and fat respond less to insulin
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 4
Beta cells compensate, then fall behind
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
Hyperglycaemia, often without symptoms
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Years of hyperglycaemia damage blood vessels
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .