Type 2 diabetes mellitus: incidence, management and prognosis

Type 2 diabetes mellitus in childhood emerged in the UK in about 2000, and now affects about 250 children or 1% of all childhood diabetes in the UK. It characteristically presents in an obese child, around the time of puberty, with osmotic symptoms of thirst and polyuria. Some children are identified co-incidentally, and a small proportion may present with decompensation and diabetic ketoacidosis. Acanthosis nigricans is a common feature. There is a significant female preponderance, with children from ethnic minorities disproportionately represented, and usually a history of type 2 diabetes mellitus in first-degree relatives. In contrast to type 1 diabetes, children with type 2 may have already have microvascular complications by the time they are diagnosed. The differential diagnosis clearly includes type 1 diabetes, usually distinguished by the presence of autoantibodies GAD65, ICA and IAA; but also diabetes secondary to monogenic causes, transplant and immunosuppression, and rarer syndromes. Management includes confirming the diagnosis of diabetes according to World Health Organisation criteria; screening for both microvascular complications and complications of metabolic syndrome; and initiating lifestyle, dietary and exercise advice to decrease calorie intake and increase energy expenditure. Children with osmotic symptoms or HbA1c greater than 8.5% should be commenced on insulin therapy then weaned off over 1–3 months. Metformin should also be instituted from diagnosis provided there is no ketoacidosis, and the dose increased to the maximum tolerated. Insulin is currently the only second line treatment licensed for use in the UK. A pragmatic approach is to offer once a day long acting insulin; and add in mealtime short acting insulin if insufficient response. The glycated haemoglobin target for optimal glycaemic control is less than 7.0%. Future treatments under investigation for paediatric use include the GLP-1 antagonists and DPPV4 inhibitors. It is hoped that the current batch of phase III studies will lead to an evidence base for better treatments in future.