This site is intended for health professionals only

Type 2 diabetes: the early-onset phenomenon

Dr SH Song
MD FRCP
Consultant Physician
Diabetes Centre
Northern General Hospital
Sheffield

Traditionally, type 2 diabetes (T2DM) is a condition that affects the middle-aged and elderly. However, the age of onset has decreased and T2DM is now found among younger patients including children and adolescents. Newly-diagnosed T2DM is reported to occur in 8-45% of young children in the USA, while in Japan, the prevalence of T2DM among junior high school children has doubled between 1976 and 1980 and 1991 and 1995, and now outnumbers cases of type 1 diabetes.(1) Early onset T2DM has also been reported in China, India, Australia and Mexico. In the UK a recent study showed that between 1996 and 1997 and 2003 and 2004 hospital admissions for new cases of T2DM in patients below 18 years of age rose by approximately 45%. This parallels the 63% rise in patient admission for obesity in the same period.(2)
Obesity, and in particular central obesity, is a major risk factor for early onset T2DM. Genetics also appears to play an important role as more than two thirds of young patients with T2DM have at least one parent with the condition. High-risk groups include women and ethnic minorities such as Asians, Pima Indians, Afro-Caribbeans and Hispanics.
The early-onset T2DM phenomenon brings a new perspective to the global diabetes epidemic and heralds a major public health issue. Obesity and the rising prevalence of T2DM in the young are consequences of our sedentary lifestyle and the far-reaching effects of globalisation and industrialisation. The onset of T2DM in the young heralds many years of disease and an increased risk of diabetes-related complications.
The pathophysiology of T2DM in the young and old appears to be similar as both include ß-cell dysfunction and insulin sensitivity defects. As with older patients, young people with T2DM patients are at risk of micro- and macrovascular complications. Nephropathy is the most common microvascular complication: a quarter of young T2DM patients have microalbuminuria at diagnosis.(3) Nephropathy occurs approximately twice as often among young T2DM subjects than those with type 1 diabetes.(4)
From a cardiovascular standpoint, early-onset T2DM appears to be the more aggressive disease. The relative risk of death from cardiovascular disease is apparently greater in the young rather than the old.(5)
A recent study from Sheffield demonstrated that early onset T2DM patients younger than 40 years of age have poorer glycaemic control despite having shorter diabetes duration, a more adverse lipid profile, higher prevalence of morbid obesity and similar prevalence of hypertension compared with a cohort aged over 40 years.(6) Despite having similar, if not more adverse cardiovascular risk profiles, the early-onset cohort, particularly women, were less likely to be treated with lipid- and blood pressure-lowering treatment than the late-onset cohort. This demonstrates a worrying misconception that young T2DM patients have a low risk of cardiovascular disease.
The appearance of T2DM in the young raises new issues in the management of diabetes. One dilemma is the diagnostic difficulty of diabetes classification. Differentiating type 2 from type 1 diabetes can be clinically challenging as central obesity among these patients is increasingly common. Other possible diagnoses include maturity-onset diabetes of the young (MODY), and certain familial conditions such as Prader-Willi syndrome and familial lipodystrophy.
Management principles, however, are the same for old and young patients: attaining physical wellbeing; good glycaemic control; and preventing or reducing the risk of microvascular and macrovascular complications. Multifactorial interventions that focus on lifestyle changes, glycaemic control and lipid and blood pressure treatment are required.
Lipid-lowering therapy, however, can present a difficult and contentious issue, as clinical trial evidence is sparse for this group of patients. Recognising early onset T2DM patients as a high-risk group, the Joint British Societies-2 guidelines recommend lipid-lowering therapy with statins for cardiovascular disease (CVD) primary prevention in patients with at least one risk factor.(7) As the number of T2DM women of child-bearing age is increasing and optimisation of CVD risk-reduction therapy involves medications (such as statins, ACE-inhibitors and angiotensin-II receptor blockers) that are contraindicative during pregnancy, adequate prepregnancy care is another important aspect of early-onset diabetes management.(8)
Since obesity and early-onset T2DM are intimately associated, it remains a high priority to install prevention strategies that help patients make lifestyle changes. There is good evidence to support the idea that increased physical activity can reduce the risk of diabetes in high-risk patients. However, this endeavour is only likely to succeed if governments and communities provide the environment within which an individual can make such lifestyle changes. Ultimately, self-motivation is the key to achieving and maintaining successful long-term lifestyle changes.

Conclusion
In conclusion, the number of young patients with T2DM is increasing as a consequence of obesity. Phenotypic features of classical T2DM are appearing at least three decades earlier in young patients. These patients have poorer glycaemic control, more adverse cardiovascular risk profiles and are less likely to be treated with cardioprotective medications than older people with diabetes. Despite their young age, these patients have an increased risk of developing diabetes-related complications and therefore should be aggressively managed. Prevention with lifestyle intervention is important in stemming the rising tide of this phenomenon.

[[nip36_28_casestudy]]

References

  1. 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;27:1798-811.
  2. Aylin P, Williams S, Bottle A. Obesity and type 2 diabetes in children, 1996-7 to 2003-4. BMJ 2005;331:1167.
  3. Fagot-Campagna A. Complications among Pima Indians diagnosed during childhood (Abstract). Diabetes 1998;47:S1:A155.
  4. Yokoyama H, Okudaira M, Otani T, et al. Existence of early-onset NIDDM Japanese demonstrating severe diabetic complications. Diabetes Care 1997;20:844-7.
  5. Hillier TA, Pedula KL. Complications in young adults with early-onset type 2 diabetes: losing the relative protection of youth. Diabetes Care 2003;26:2999-3005.
  6. Song SH, Hardisty CA. Cardiovascular risk profile of early and later onset type 2 diabetes. Practical Diabetes Int 2007;24:20-4.
  7. British Cardiac Society, British Hypertension Society, Diabetes UK, Heart UK, Primary Care Cardiovascular Society, Stroke Society. Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice. Heart 2005;91 Suppl V:1-52.
  8. Confidential Enquiry into Maternal and Child Health (CEMACH). Pregnancy in women with type 1 and type 2 diabetes in 2002-2003, England, Wales and Northern Ireland. London: CEMACH; 2005.