Investigations

Simple investigations are often sufficient to confirm the clinical diagnosis of diabetes mellitus:

• urinalysis for glucose and ketones: it should be remembered some reagent strips give a false negative result for glucose in the presence of significant ketonuria
• plasma glucose measurement: reagent strip and laboratory measurement of random and/or fasting plasma glucose

Other investigations include:

• plasma bicarbonate and pH measurements
• urea, creatinine and electrolyte measurements
• glycosylated haemoglobin
• white cell count +/- cultures as a screen for precipitating infection

Investigations performed for research purposes may include:

• anti-insulin and anti-islet cell antibodies
• C-peptide levels following carbohydrate challenge

It is important to remember to minimise venesection in the newly diagnosed diabetic; the last thing one wishes to create is a phobia of needles.