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.^2,3 This early-onset (also called ‘young-onset’) type 2 diabetes is concerning because it results in a longer lifetime exposure to hyperglycaemia and consequent complications. There is also emerging evidence that early-onset type 2 diabetes is a more aggressive disease than later-onset type 2 diabetes and is accompanied by the earlier onset and more rapid progression of macrovascular and microvascular complications.^3–6 

Definitions and diagnosis 

Early-onset type 2 diabetes is usually defined as occurring under the age of 30 years.¹ This can be further separated into child and adolescent (<18 years) and young adult (<30 years) onset. 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 to differentiate between type 1 diabetes, latent autoimmune disease of adults, type 2 diabetes and monogenic diabetes (Table 1). Careful diagnostic assessment is required, because this has a major impact on management and outcome.⁷ 

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. For more information, refer to The Royal Australian College of General Practitioners’ Emergency management of hyperglycaemia in primary care. 

Screening and risk factors 

Risk factors for early-onset type 2 diabetes include:¹ 

• a maternal history of type 2 diabetes or gestational diabetes during an individual’s gestation 
• a family history of type 2 diabetes in a first-degree relative 
• certain ethnicity (Aboriginal and Torres Strait Islander, South Asian, South-East Asian, North African, Latin American, Middle Eastern, Māori or Pacific Islander people [includes individuals of mixed ethnicity]) 
• clinical evidence of insulin resistance (polycystic ovary syndrome, acanthosis nigricans, dyslipidaemia, hypertension) or existing macrovascular disease, impaired fasting glucose, impaired glucose tolerance or history of gestational diabetes 
• the use of antipsychotic medications. 

There are no specific tools currently available for the 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 suboptimal glycaemic management,10 diastolic hypertension, an 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 the cohort of people with early-onset type 2 diabetes, life expectancy is reduced by 14 years for males and 16 years for females compared with those without diabetes.3 An Australian study showed 11% mortality over 20 years in a cohort of young adults diagnosed between the ages of 15 and 30 years.¹¹  

The treatment of people with 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.⁷ 

Structured education is fundamental to long-term self-care and can benefit young people. Developing programs tailored to their needs and addressing factors such as diabetes-related distress, depression and other socioeconomic issues can enhance young people’s participation and support their diabetes management more effectively. 

Lifestyle changes, including weight loss and exercise, are recommended as first-line therapy. However, limited studies are available to inform management. Although lifestyle changes can provide benefits, emerging evidence suggests these changes may not be easily maintained once support programs ceases, and there is low-level evidence that the benefit provides protection against future cardiovascular disease.^13,14 Limited data suggest that metabolic surgery may be a treatment option for some.¹² 

The use of glucose-lowering medication is generally extrapolated from management algorithms for people with older-onset type 2 diabetes. There is a paucity of data, especially with the newer therapies, in people aged <18 years. It is likely that people with early-onset type 2 diabetes will require early initiation of insulin.⁷ 

Treatments to address cardiovascular risk factors are again based on evidence from older person groups. To reduce the lifetime risk of coronary heart disease, early and aggressive treatment of cardiovascular risk factors in young people with type 2 diabetes is recommended;^12,15 however, there is evidence that the use of cardioprotective treatments, such as statins and antihypertensive medication, in the younger age group is suboptimal.³ This might be due to reluctance by doctors to prescribe such lifelong therapies to younger people, especially women,¹² 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 emphasises the need for education and for healthcare providers to ensure they provide accessible, patient-centred, coordinated, continuous and effective care during this period. This period of ‘vulnerability’ may require the general practitioner and treating team to specifically plan for that person’s support needs and maintain adequate monitoring and complication screening. 

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

It is recommended that all child, adolescent and young-adult (aged 18–30 years) people with type 2 diabetes be referred to an endocrinologist or, if not accessible, a specialist physician with an interest in diabetes. For people aged 18–30 years with early-onset type 2 diabetes, consider referral and/or shared care, because management can be difficult and there is a high burden of complications. 

Further reading 

• Alberti G, Zimmet P, Shaw J, et al. Type 2 diabetes in the young: The evolving epidemic: The international diabetes federation consensus workshop. Diabetes Care 2004;27(7):1798–811. doi: 10.2337/diacare.27.7.1798. 
• 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. doi: 10.2337/dci18-0052. 
• Azzopardi P, Brown AD, Zimmet P, et al. 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. doi: 10.5694/mja12.10036. 
• 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. doi: 10.1038/nrendo.2011.183. 
• 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. doi: 10.7326/M18-1900. 
• Nadeau KJ, Anderson BJ, Berg EG, et al. Youth-onset type 2 diabetes consensus report: Current status, challenges, and priorities. Diabetes Care 2016;39(9):1635–42. doi: 10.2337/dc16-1066. 
• Sattar N, Rawshani A, Franzén S, et al. Age at diagnosis of type 2 diabetes mellitus and associations with cardiovascular and mortality risks. Circulation 2019;139(19):2228–37. doi: 10.1161/CIRCULATIONAHA.118.037885. 
• 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. doi: 10.1136/bmjdrc-2014-000044.