Early-onset type 2 diabetes

In recent years there has been an increase in the incidence and prevalence of type 2 diabetes in children, adolescents and young adults.^1,2 This early-onset (also called ‘young-onset’) type 2 diabetes is concerning, as it results in a longer lifetime exposure to hyperglycaemia and the consequent complications. There is also emerging evidence that early-onset type 2 diabetes is a more aggressive disease compared with later-onset type 2 diabetes, and is accompanied by earlier onset and more rapid progression of macrovascular and microvascular complications.^2–4

Table 1.

 Comparison of type 1 diabetes, type 2 diabetes and maturity-onset diabetes  of the young (MODY)^5–7

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Definitions and diagnosis

Early-onset type 2 diabetes is usually defined as occurring under the age of 40 years. This can be further separated into child and adolescent (<18 years) and young adult (<25 years). However, there is no consistency of definitions across the literature, especially of the upper age limit. Although this handbook refers only to the young adult group, there is clearly a continuum across the age groups.

Unlike older-onset type 2 diabetes, this group can offer a diagnostic challenge for general practitioners (GPs) to differentiate between type 1 diabetes, latent autoimmune disease of adults, type 2 diabetes and maturity-onset diabetes of the young (MODY; Table 1). Careful diagnostic assessment is required, as this has a major impact on management and outcome.⁵

For children and adolescents, hyperglycaemia (at levels diagnostic of diabetes) can be a medical emergency, and immediate referral to an emergency department or, if not available, urgent consultation with a specialist is strongly recommended. Refer to The Royal Australian College of General Practitioners’ (RACGP’s) Emergency management of hyperglycaemia in primary care for more information.

Screening and risk factors

Risk factors for early-onset type 2 diabetes include overweight/obesity, sedentary behaviour, lower socioeconomic status, ethnicity (eg Australian Aboriginal and Torres Strait Islander peoples, Pacific Islander, Hispanic, Asian peoples), a strong family history of type 2 diabetes, previous gestational diabetes, in utero exposure to type 2 diabetes and low birth weight. The risk is also significantly higher in women diagnosed with polycystic ovary syndrome.^2,5,9

There are no specific tools currently available for screening or early detection of early-onset type 2 diabetes, other than maintaining a high index of suspicion, especially in high-risk groups.

Treatment challenges

Compared with late-onset type 2 diabetes, the early-onset group is more likely to have sub-optimal glycaemic control, diastolic hypertension, earlier need to initiate insulin, and a greater burden of diabetes-related complications (Box 1), resulting in a reduced quality of life, greater morbidity and premature mortality.

In early-onset type 2 diabetes, life expectancy is reduced by 14 years in males and 16 years in females compared with their non-diabetic cohort.² An Australian study showed 11% mortality over 20 years in a cohort of young adults diagnosed between 15 and 30 years of age.¹⁰

Treatment of early-onset type 2 diabetes is limited by a lack of evidence, and current recommended treatment strategies are extrapolated from the evidence base for older-onset type 2 diabetes.⁵

Structured education is fundamental to long-term self-care. However, there are obstacles in engaging young adults, including a lack of specific programs for their needs and higher rates of diabetes-related distress, depression and other socioeconomic issues that may adversely impact their participation.

Lifestyle changes, including weight loss and exercise, are recommended as first-line therapy. However, limited studies are available to inform management. While lifestyle changes can provide benefits, emerging evidence suggests these changes are not maintained once the program ceases, and there is no evidence that the period of benefit provides any protection against future cardiovascular disease. Limited data suggest that metabolic surgery may be a treatment option for some.⁹

Use of glucose-lowering medication is generally extrapolated from management algorithms for older-onset type 2 diabetes patients. There is a paucity of data, especially with the newer therapies, in people aged <18 years. It is likely that early-onset type 2 diabetes patients will require early initiation of insulin.⁵

Treatments to address cardiovascular risk factors are again based on evidence from older patient groups. To reduce lifetime risk of coronary heart disease, early and aggressive treatment of cardiovascular risk factors in young people with type 2 diabetes is recommended;^9,11 however, there is evidence that use of cardioprotective treatments, such as statins and anti-hypertensive medication, in the younger age group is suboptimal.² This might be due to reluctance by doctors to prescribe such lifelong therapies to younger people, especially women,⁹ and the fact that cardiovascular risk calculators are reliable in older age groups only.

Adherence to medication and follow-up is also a problem in younger age groups. This can be a challenge for adequate management, and it emphasises the need for education and for healthcare providers to ensure they provide accessible, patient-centred, coordinated and continuous effective care during this period.

Pre-pregnancy counselling and/or contraception is imperative in this age group to offset preventable diabetes-related pregnancy and fetal complications (refer to the section ‘Type 2 diabetes, reproductive health and pregnancy’).

It is recommended that all child, adolescent and young-adult (aged <25 years) patients with type 2 diabetes be referred to an endocrinologist or, if not accessible, a specialist physician with an interest in diabetes. For patients aged ≥25 years with early-onset type 2 diabetes, consider referral and/or shared care, as management can be difficult and there is a high burden of complications.

• Alberti G, Zimmet P, Shaw J, Bloomgarden Z, Kaufman F, Silink M. Type 2 diabetes in the young: The evolving epidemic: The International Diabetes Federation consensus workshop. Diabetes Care 2004;27:179.
• Arslanian S, Bacha F, Grey M, Marcus MD, White NH, Zeitler P. Evaluation and management of youth-onset type 2 diabetes: A position statement by the American Diabetes Association. Diabetes Care 2018;41(12):2648–68.
• Azzopardi P, Brown AD, Zimmet P, et al; Baker IDI Heart, Diabetes Institute. Type 2 diabetes in young Indigenous Australians in rural and remote areas: Diagnosis, screening, management and prevention. Med J Aust 2012;197(1):32–36.
• Charles J, Pollack A, Britt H. Type 2 diabetes and obesity in young adults. Aust Fam Physician 2015;44(5):269–70.
• Chen L, Magliano DJ, Zimmet PZ. The worldwide epidemiology of type 2 diabetes mellitus – Present and future perspectives. Nat Rev Endocrinol 2011;8(4):228–36.
• Ke C, Lau E, Shah BR, et al. Excess burden of mental illness and hospitalization in young-onset type 2 diabetes: A population-based cohort study. Ann Intern Med 2019;170(3):145–54.
• Nadeau KJ, Anderson BJ, Berg EG, et al. Youth-onset type 2 diabetes consensus report: Current status, challenges, and priorities. Diabetes Care 2016;39,1635.
• Sattar N, Rawshani A, Franzén S, et al. Age at diagnosis of type 2 diabetes mellitus and associations with cardiovascular and mortality risks findings from the Swedish National Diabetes Registry. Circulation 2019;139(19):2228–37.
• Song SH. Complication characteristics between young-onset type 2 versus type 1 diabetes in a UK population. BMJ Open Diabetes Res Care 2015;3(1):e000044.