Introduction
 

The prevalence of type 2 diabetes mellitus  has  been  increasing over the past decade globally, and is largely attributed to recent global industrialisation which has created an affluent environment with abundant, readily available, calorie - dense food, and an increasingly sedentary lifestyle, of greater concern is the disturbing  and alarming increase of type 2 diabetes being diagnosed in children and  adolescents over the past few years.

On the Rise

Until recently, type I diabetes was the only type of diabetes considered to be prevalent among children, with only 1 to 2% of children considered to have type 2 diabetes or other rare forms of diabetes. However, recent reports and studies have provided alarming estimates of the markedly increased frequency of childhood type 2 diabetes from the USA, Japan, Libya, Bangladesh, Australia and Canada. In the past few years, about 50% of all children with newly diagnosed diabetes in our local paediatric tertiary centre have been classified as type 2 (internal audit data). a dramatic increase compared to 10 to 20 years ago when it was considered rare.

Serious and Costly

Type 2 diabetes is a serious and costly disease with excess mortality and long term morbidity, with macro- and micro-vascular complications such as cardiovascular disease, diabetic nephropathy and end-stage renal failure, diabetic retinopathy and ultimately loss of visual acuity. If the rapidly increasing incidence of type 2 diabetes in children is not curbed, our society will face major challenges in the very near future as the burden of diabetes and its disabling complications will affect many more young individuals at the prime of their lives. They will probably spend most of their adulthood putting up with the attendant risks, taking medications, and suffer disabling consequences which will affect their quality of life.

What are the characteristics of children with type 2 diabetes. and how do they differ from children with type 1 diabetes? Children with type 1 diabetes typically present with polydipsia, polyuria, polyphagia (the 3 Ps) and weight loss. The classical teaching is that they are usually not overweight. As the population becomes increasingly overweight, it is not surprising these days that children with type 1 diabetes can be obese 'coincidentally'.

Symptoms

Children with type 1 diabetes may have short duration of symptoms, and almost 40% may present with diabetic ketoacidosis. About 5 to 15% of children with type 1 diabetes have a first or second degree relative with the same condition. Children with type 2 diabetes, in contrast, are usually asymptomatic and presented with incidental glycosuria or hyperglycaemia from opportunistic screening, and indeed many are now diagnosed because of increased awareness of associated risk factors which lead to screening by their doctors. Some may have mild polydipsia and polyuria, with little or no weight loss, and less commonly can present with ketoacidosis or hyperosmolar hyperglycaemic nonketotic coma. Most children with type 2 diabetes are overweight or obese (up to 85%), and sometimes this can be masked by significant weight loss just prior to presentation. They usually have a strong family history of the condition, and it is estimated that up to 80% have at least one parent with diabetes, and 74 to 100% have a first or second degree relative with type 2 diabetes, implying that the heritability of this condition is probably higher than that of type 1 diabetes.

Children with type 2 diabetes usually present after 10 years of age, when they are in puberty. This coincides with growth hormone and sex hormone surges during this period which aggravates any underlying insulin resistance. However, as our paediatric population gets increasingly obese, prepubertal children may also develop the condition. Children with type 2 diabetes often have other features of insulin resistance, namely acanthosis nigricans, hypertension, non-alcoholic fatty liver disease, dyslipidemia, and polycyctic ovarian syndrome.

About 90% of children with type 2 diabetes have acanthosis nigricans, a pigmented velvety thickened skin found at skin folds, such as the neck, axilla and groin. The initial classification is usually based on the clinical picture at presentation, but sometimes it can be aided by the c-peptide, insulin and antibodies levels. Children with type 2 diabetes may have normal or elevated fasting c-peptide and insulin levels. Sometimes these levels may be low at presentation secondary to glucotoxic effects on the pancreatic islet cells. Children with type 1 diabetes usually have low insulin and c-peptide levels. About 90% of Caucasian and 60% of Asian children with type 1 diabetes may have autoanubodies such as islet cell antibodies (ICA), glutamic acid decarboxylase antibodies (anti-GAD, and insulinoma-associated-2 (IA-2) antibodies.

Diagnostic Criteria

The diagnostic criteria of diabetes as outlined by the American Diabetes Association (ADA) also applies to children (table I). Which group of children should be tested then? The ADA consensus panel recommends that children who are overweight with any two risk factors should be tested every two years starting at ten years of age, or at the onset of puberty (table 2). As we do not have BMI percentile chart for our local children at the moment, the cut off value of 120% of ideal weight for height as recommended by our school health service can be used to identify overweight children locally, using the local weight for height chart.

Treatment

The goal of treatment is to normalise blood glucose values and HbA1c, and control of associated conditions like hypertension and hyperlipidemia. Patients who are not ill or in diabetic ketoacidosis at presentation may not need insulin. They can be treated with proper dietary advice, exercise and weight reduction. Eventually, most will need drug therapy.

Metformin has been shown to be safe and effective for treatment of type 2 diabetes in children. While most other oral hypoglycaemic agents are not FDA approved for treatment of diabetes in children, most paediatric diabetologists will use oral hypoglycaemic agents singly or in combination when possible, instead of insulin. Use of oral agents is more convenient and less painful for the child and family, and, in turn will help to ensure better compliance.

However, when it is difficult to classify the child as type 1 or 2 disease, or if the child is ill with ketosis / ketoacidosis / dehydration, insulin therapy may be initiated, and with time and treatment, metabolic control can be established and the condition can be re-evaluated, with tapering of insulin and introduction of oral agents as the patient's glycaemic control improves. Children should be educated on the benefits of a healthy, active lifestyle and good dietary habits, which will improve glycaemic control, and reduce excessive adiposity and insulin resistance. Monitoring for complications should be carried out annually with retinal photography, microalbuminuria screening, and checking blood lipid levels. Microalbuminuria and/or hypertension can be treated with ACE inhibitors, which offer additional benefits of preventing diabetic nephropathy.

Conclusion

Primary prevention is imperative to prevent a potential onslaught on the healthcare system in the very near future. Thus, attention and efforts should be directed at our children to instill proper concepts of a healthy lifestyle. Early intervention will have significant long term beneficial effects.

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• Symptoms of diabetes plus casual plasma glucose concentration ≥200 mg/dl (11.1 mmol/l). Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss.

In the absence of unequivocal hyperglycaemia with acute metabolic decompensation, these criteria should be confirmed by repeat testing on a different day. The third measure (OGTT) is not recommended for routine clinical use. Adapted from the Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (1).

TABLE 4. Testing for Type 2 Diabetes in Children

       • Criteria*

• Test: FPG preferred

Tables I and 2 are from Type 2 diabetes in children and adolescents. American Diabetes Association. Pediatrics. 2000; 105( 3 Pt 1):671-80.

1. Type 2 diabetes in children and adolescents. American Diabetes Association. Pediatrics. 2000: 105(3 Pt I ):67 I -80.