A THIRSTY BOY
History
Steven is a 4-year-old boy seen in the paediatric day unit with a 2-week history of polydipsia and polyuria. Having been dry at night for some time, he has also started wetting the bed. His mother thinks that he has lost some weight. He has been less cheerful than usual and hasn’t wanted to go to school – his mother has put this down to tiredness at the end of his first term. She and her mother have hypothyroidism. There is no significant past medical history and he is fully immunized. He has a 2-year-old brother who is well.
Examination
Steven is playing happily in the playroom. His weight is on the 9th centile and his height is on the 50th centile. His trousers are a bit loose round his waist. He is afebrile. He is not dehydrated. His pulse is 84 beats/min and his capillary refill time is 2 s. Examination of the respiratory and abdominal systems is normal.
INVESTIGATIONS
Normal Haemoglobin 12.3 g/dL 11.5–15.5 g/dL
White cell count 8.4 109/L 6–17.5 109/L
Platelets 365 109/L 150–400 109/L
Sodium 138 mmol/L 138–146 mmol/L
Potassium 4.5 mmol/L 3.5–5.0 mmol/L
Urea 4.2 mmol/L 1.8–6.4 mmol/L
Creatinine 46 µmol/L 27–62 µmol/L
Glucose 22.4 mmol/L 3.3–5.5 mmol/L
Venous blood gas
pH 7.35 7.35–7.45
PCO2 4.3 kPa 4.7–6.4 kPa
Bicarbonate 19 mmol/L 22–29 mmol/L
Urinalysis Glucose +++, ketones +++
Questions
• What is the diagnosis?
• What should happen next?
• List the topics that need to be discussed with his family?
Medicine
The diagnosis is type 1 diabetes mellitus (T1DM), by far the commonest form of diabetes in childhood characterized by pancreatic β-cell dysfunction with insulin deficiency. The precise mechanism is not understood, but environmental factors probably ‘trigger’ a T-cell-mediated autoimmune process in those genetically susceptible (although only about 10 per cent have a family history at presentation). There may be a history of other autoimmune diseases. The incidence is rising. The incidence of type 2 is also rising alongside obesity. Although this boy has ketonuria, he is not acidotic and does not have diabetic ketoacidosis (DKA) – a widely accepted biochemical definition being a pH 7.30 and/or a bicarbonate 15 mmol/L. Nor is he vomiting or showing signs of sepsis. Therefore he does not need intravenous fluids or intravenous insulin. Only about 10–20 per cent of children present with DKA, usually pre-school children in whom the diagnosis has not been considered. Childhood DKA has a mortality rate of approximately 0.2 per cent, usually from cerebral oedema due to the use of excessive fluids and/or rapid changes in blood glucose. He now needs to start regular subcutaneous insulin. Current best practice suggests that insulin is best delivered by a ‘basal bolus’ regime – background ‘basal’ insulin given once daily with rapid-acting ‘bolus’ insulin at mealtimes. Alternatives are twice-daily injections of pre-mixed long and rapidly acting insulins or insulin via a pump. The impact of the diagnosis of T1DM should never be underestimated (see Case 87, p. 255 in relation to the breaking of bad news to families). At diagnosis, he and his family will start a detailed education programme. Education is provided by a multidisciplinary team, including specialist nurses and dieticians. The aspects of management that need to be discussed include:
• how to give insulin – to a probably reluctant 4-year-old
• regular finger-prick blood testing – up to four times daily
• interpreting blood glucose results and altering insulin
• recognition and treatment of hypoglycaemia – ‘hypos’ really worry parents and older patients, especially at night
• management during intercurrent illness, e.g. flu
• blood or urine ketone estimations
• who to contact in an emergency
• diet – matching insulin to carbohydrate in a ‘basal-bolus’ regime • school – trusting staff in everyday care
• peer group relationships – diabetes risks making children feel ‘different’
• exercise
• the ‘honeymoon’ period
• long-term complications – discuss even at outset because many families know about and fear complications and need objective information
• using glycosylated haemoglobin (HBA1c) to measure overall control
• membership of local and/or national support groups.
KEY POINTS
• The cardinal features of type 1 diabetes are polydypsia and polyuria.
• Most patients do not present in DKA.
• Patients with DKA are acidotic (pH 7.30) as well as having ketonuria.
• Education and support from a multidisciplinary specialist team are crucial.
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