Making the referral Te finding of ketonuria or ketonaemia, in conjunction with an elevated blood glucose, is highly suspicious for type 1 diabetes and mandates an urgent referral to a diabetes centre. Te timing with which the individual actually needs to be seen in the diabetes centre will depend on the age and clinical state of the individual, but I would always recommend that this initial referral happens by telephone rather than by mail. I appreciate that making telephone contact with specialists can be time consuming and frustrating for colleagues in primary care, but letters and emails can go astray or lie unread for several days and a delay of even one or two days can mean the difference between a patient who can be managed exclusively on an out-patient basis and one who is admitted to hospital with severe metabolic decompensation. If the patient does not have elevated blood or urine ketones, then
there is usually less urgency about initiation of treatment. If the individual has central obesity and evidence of hypertension and dyslipidaemia, a diagnosis of type 2 diabetes can be made but remember the rare possibilities of Cushing’s syndrome and acromegaly. If an individual is slim (body mass index <25 kg/ m2), then type 2 diabetes is a less plausible diagnosis and that is when real consideration needs to be given to some of the other potential causes listed above. By definition, if the individual is slim, then there must be a degree of insulin deficiency rather than insulin resistance. One caveat to that is ethnicity. Individuals of South Asian origin have more central obesity (and thus more insulin resistance) for a given body mass index (BMI) than individuals of Caucasian origin. Tus, in insulin resistance terms, a BMI of 23 kg/m2 in a South Asian man is roughly equivalent to a BMI of about 25 kg/m2 in a Caucasian man. Do not presume that because an individual is young that they
must have type 1 diabetes. Type 2 diabetes used to occur exclusively in middle-aged and older adults, but in our increasingly obese societies we are now seeing young adults and even teenagers presenting with typical type 2 diabetes.
n Professor Mark WJ Strachan is Associate Medical Director at the Western General Hospital, Edinburgh, and an Honorary Professor at the University of Edinburgh
SUMMER 2014
Key points • HbA1c or glucose can be used to diagnose diabetes, but there are certain situations where HbA1c may be unreliable.
• Obtain a second, confirmatory test in asymptomatic patients but never delay therapy in symptomatic patients, children and individuals who are ill.
• Type 1 diabetes can occur at any age and in individuals who are overweight.
• Check urine or blood ketone levels in all people with a new presentation of diabetes. Phone your local diabetes centre for advice if you suspect someone has type 1 diabetes.
• Always think to yourself: “Why has this person developed diabetes?” Make the correct diagnosis of the type of diabetes and do not presume that an older individual has type 2 diabetes and that a younger individual has type 1 diabetes.
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