Type 1 diabetes mellitus vs Type 2 diabetes mellitus
How to tell Type 1 diabetes mellitus and Type 2 diabetes mellitus apart when a board question makes them look alike.
Type 1 is autoimmune absolute insulin deficiency with low C-peptide and ketosis; type 2 is insulin resistance with preserved early C-peptide.
Side by side
Autoimmune beta-cell destruction causing absolute insulin deficiency, childhood or lean adult onset, ketosis tendency, and islet autoantibodies.
Insulin resistance with relative insulin deficiency, often associated with obesity, acanthosis nigricans, metabolic syndrome, and gradual hyperglycemia.
T-cell mediated autoimmune destruction of pancreatic beta cells reduces endogenous insulin and C-peptide.
Peripheral insulin resistance increases beta-cell demand until beta-cell dysfunction produces persistent hyperglycemia.
Low C-peptide, positive islet autoantibodies, DKA tendency, and need for insulin support type 1 diabetes.
Normal or high early C-peptide, insulin resistance markers, hypertriglyceridemia, and acanthosis support type 2 diabetes.
The trap
Adults can develop autoimmune diabetes and children can develop type 2, so age alone is unsafe.
Watch it explained
Test it nowThe repair move
For diabetes type, use insulin biology and antibodies before relying on age or body habitus.
Try a free question
CoreA lean adolescent presents with polyuria, weight loss, diabetic ketoacidosis, low C-peptide, and anti-GAD antibodies. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Type 1 diabetes mellitus. DKA with low C-peptide and islet autoantibodies points to autoimmune type 1 diabetes.
Why the other choices are tempting
- B. Type 2 diabetes is insulin resistance and usually has preserved early C-peptide.
- C. MODY is monogenic beta-cell dysfunction with autosomal dominant family pattern and usually no autoantibodies.
- D. Primary polydipsia causes excess water intake, not autoimmune insulin deficiency.
- E. Cushing syndrome can cause hyperglycemia but does not explain DKA with islet antibodies.
Flashcards
Tap a card to flip it.
What lab points to type 1 diabetes?
Low C-peptide with islet autoantibodies points to type 1 diabetes.
What clinical pattern points to type 2 diabetes?
Obesity, acanthosis nigricans, insulin resistance, and gradual hyperglycemia point to type 2 diabetes.
Quick answers
What is the fastest way to tell Type 1 diabetes mellitus from Type 2 diabetes mellitus?
Type 1 is autoimmune absolute insulin deficiency with low C-peptide and ketosis; type 2 is insulin resistance with preserved early C-peptide.
What is the key clue for Type 1 diabetes mellitus?
Autoimmune beta-cell destruction causing absolute insulin deficiency, childhood or lean adult onset, ketosis tendency, and islet autoantibodies.
What is the key clue for Type 2 diabetes mellitus?
Insulin resistance with relative insulin deficiency, often associated with obesity, acanthosis nigricans, metabolic syndrome, and gradual hyperglycemia.
What is the common trap with Type 1 diabetes mellitus vs Type 2 diabetes mellitus?
Adults can develop autoimmune diabetes and children can develop type 2, so age alone is unsafe.