features differentiating between type 1 and type 2 diabetes mellitus

Last edited 06/2020 and last reviewed 07/2021

differentiating between type 1 and type 2 diabetes

Clinical and biochemical clues to differentiate type 1 from type 2 diabetes

Factors favouring (but not indicative of) type 1 diabetes (1):

• rapid onset of osmotic symptoms
  
  
• normal or low body weight or rapid weight loss
  
  
• ketonaemia >=3mmol/l on capillary testing or ketonuria
  
  
• family or personal history of other autoimmnune conditions
  
  
• failure to respond to oral therapy
  
  
• positive antibody test (anti-GAD, insulin autoantibodies (IAA) and islet cell antibodies (ICA) most commonly used)
  
  
• urine C-peptide:creatinine ratio less than 0.5nmol/l

The presence of one or more of these clues may point to a diagnosis of type 1 diabetes but absence does not exclude it (1).

A schemata for helping to to distinguish Type 1 from Type 2 diabetes has been detailed (2):

Reference:

• (1) The Association of British Clinical Diabetologists (ABCD) 2016. Standards of care for management of adults with type 1 diabetes
• (2) The North West London Health and Care Partnership. North West London Diabetes Guidelines (Accessed 17/6/2020).