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
Comparison of type 1 diabetes, type 2 diabetes and maturity-onset diabetes of the young (MODY)5–7
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.
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
Box 1. Complications in early-onset type 2 diabetes compared with older-onset type 2 diabetes2,9
Lifetime risk of complications greater with onset at a younger age
Life expectancy reduced
Non-alcoholic fatty liver disease is twice as common
Earlier onset of microalbuminuria and end-stage renal failure
Earlier onset and greater prevalence of diabetic retinopathy
Earlier onset of neuropathy
Apolipoprotein B concentration is higher despite statin therapy
Risk of myocardial infarction is 14 times higher compared with age cohort, while older-onset type 2 diabetes risk is 2–4 times higher
Early-onset of diastolic myocardial dysfunction
Reduced fertility, and greater pregnancy complications
Risk of premature decline in cognitive function
Higher rate of diabetes-related psychological distress and psychological issues, especially depression
Limited work capacity and consequent socioeconomic impact
Reduced quality of life