ABC of Diabetes
ABC of Diabetes
Tim Holt1 and Sudhesh Kumar2
1Nuffield Department of Primary Care Health Sciences, Oxford University, UK
2Warwick Medical School, University of Warwick; and WISDEM, University Hospital, Coventry, UK
Diabetes produces a variety of clinical presentations, from acute to gradual onset.
The diagnosis should be based on two separate tests, unless the patient is clearly symptomatic, in which case only one positive test is required.
A combination of genetic and environmental factors contribute to the risk of diabetes.
Impaired glucose regulation is an important risk factor, both for future diabetes and cardiovascular disease.
Distinction between random and fasting samples is essential in interpreting the significance of borderline blood glucose levels. Introduction
Diabetes mellitus is a common metabolic disorder that is defined by chronic hyperglycaemia. There are myriad underlying causes for the hyperglycaemia but, currently, much of our approach to treatment is empirical. Besides symptoms related to hyperglycaemia itself, such as thirst, polyuria and weight loss, it may also cause potentially life-threatening acute hyperglycaemic emergencies. It is a major cause of morbidity and premature mortality from long-term complications such as cardiovascular disease, blindness, renal failure, amputations and stroke. With good control of hyperglycaemia established early on, and continued life-long, an individual with diabetes can enjoy a good quality of life and reduce the risk of these long-term complications that are so detrimental to their life and wellbeing.
Prevalence of diabetes
In the United Kingdom, we have an estimated 2.9 million people with diabetes. The prevalence of both type 1 and type 2 diabetes is increasing. Type 2 diabetes is increasing far more rapidly, driven by increasing life expectancy and the epidemic of obesity. It is believed that there will be as many as 300 million people with diabetes worldwide by the year 2025. Most of this increase will occur in developing countries. The majority of children have insulin-requiring type 1 diabetes, while the vast majority of those aged over 25 years will have type 2 diabetes ( Figure 1.1 ).
Figure 1.1 Projected prevalence of diabetes in 2025.
Source: World Health Organisation (1998). Reproduced with permission of World Health Organisation.
Types of diabetes
The types of diabetes have been classified by the WHO. Type 1 diabetes (previously referred to as insulin-dependent diabetes mellitus or IDDM) is due to absolute insulin deficiency and is usually an autoimmune disease, leading to the destruction of the insulin-secreting beta cells in the pancreas. In some cases, the cause of destruction of the beta cells is not known.
Type 2 (previously known as non-insulin dependent diabetes mellitus or NIDDM) results from relative insulin deficiency that may be associated with varying degrees of insulin action defects, known collectively as insulin resistance.
For a practising clinician, the implication of this diagnosis is that patients with type 1 diabetes require insulin straight away and insulin should not be stopped, as it is life-preserving. Type 2 patients can progress through several stages, and may require insulin later on in their disease.
Risk factors for diabetes
Genetic susceptibility is important for both types of diabetes. Family history of type 1 diabetes, or other autoimmune diseases such as autoimmune thyroid disease, is associated with a higher risk of developing type 1 diabetes in the family. Inheritance in type 2 diabetes is far more complex, as there are m