Which of the following is NOT a feature of type 1 diabetes mellitus?

Correct answer: C. Insulin resistance at peripheral tissues

• A. Autoimmune, T-cell mediated destruction of pancreatic beta cells is the core pathology of type 1, and it is usually accompanied by detectable autoantibodies such as anti-GAD65 and anti-islet cell antibodies.
• B. Ketoacidosis is far more typical of type 1, because absolute insulin deficiency permits unrestrained lipolysis and ketone production. Type 2 patients retain enough insulin to suppress ketogenesis and are more prone to hyperosmolar hyperglycaemic state.
• C. CORRECT as the EXCEPTION. Insulin resistance is the defining abnormality of type 2 diabetes, not type 1. In type 1 the peripheral tissues respond normally to insulin — the problem is that there is no insulin to respond to, because the beta cells producing it have been destroyed. Type 1 is a state of absolute insulin DEFICIENCY; type 2 is a state of resistance with relative deficiency.
• D. Type 1 characteristically presents in childhood or adolescence, though latent autoimmune diabetes in adults (LADA) is a recognised later-onset form.

Note: For the dental appointment the practical difference is hypoglycaemia risk. Type 1 patients on insulin can drop precipitously if they have taken their dose and skipped a meal — confirm they have eaten, schedule mid-morning, and keep a fast-acting carbohydrate source in the operatory.