Diabetes: epidemiology, diagnosis

1 - Epidemiology

It is now estimated that 15% are insulin-dependent diabetics, 85% non-insulin dependent. Diabetes is a public health problem. In Europe the number of diabetics is estimated at 30 million, and in the United States 15 million diabetics for half-ignored. Around the world, there are 100 million diabetics.The term diabetes actually covers two different diseases:

1. Insulin-dependent diabetes (type 1), which occurs most often before the age of 20 and represents 10 to 15% of diabetes  
2. Noninsulin-dependent diabetes (type 2), which occurs most often after the age of 50 and represents 85 to 90% of diabetes.

It is non-insulin-dependent diabetes that poses a public health problem. Its prevalence increases with aging, urbanization, sedentarization and the development of obesity in the populations of industrialized countries. However, this disease does not spare the underdeveloped countries where non-insulin-dependent diabetes sometimes reaches a prevalence of 20 to 30%, due to a genetic predisposition coupled with a rapid change in lifestyle: brutal urbanization, sedentarisation and alcoholization of populations.Diabetes is a significant financial cost because of the high rate of degenerative complications. Thirteen per cent of dialysis patients in France are diabetic while this rate exceeds 30% in the United States. It is the same in the Scandinavian countries and in Reunion Island. In fact, 50 to 75% of dialysis diabetics are non-insulin dependent diabetics. Diabetes remains the leading medical cause of blindness before age 50 in developed countries.Five to 10% of diabetics will one day have a toe, foot or leg amputation, 4/5 of whom are non-insulin dependent diabetics. In France, there are approximately 3 to 5,000 amputees per year in diabetics. A quarter of hospital days for diabetes are due to podiatric problems. The cost of diabetes is estimated at 35 billion francs. To combat this cost, the Saint Vincent Declaration adopted in 1989 by representatives of the World Health Organization (WHO), European governments and organizations of patients, recalled the good medical practices in diabetology. It has set a goal, within 5 years, a reduction of one third to half of the complications of diabetes. Several studies have shown that changing the organization of care to obtain training for patients themselves can reduce the rate of amputations by 50%.

2 - Definition of diabetes mellitus (DM Diabetes mellitus)

The definition of diabetes is based on the glycemic threshold at risk of microangiopathy, particularly retinopathy. Diabetes is defined as chronic hyperglycemia, fasting blood glucose greater than 1.26 g / l (7 mmol / l) twice. This definition is based on several prospective epidemiological studies that have consistently shown that when the second hour glucose level of oral glucose tolerance (OGTT) is greater than or equal to 2 g / L, there is a risk of occurred within 10 to 15 years following diabetic retinopathy. Since a fasting glucose level greater than or equal to 1.26 g / l corresponds to a blood glucose level at the 2nd hour of the OGTT greater than or equal to 2 g / l, it is no longer necessary to resort to 'gold standard' of the OGTT.
To carry the diagnosis of diabetes, it is not useful to measure insulinemia or C-peptide or anti-islet antibodies, nor even to ask for an ultrasound or a pancreatic CT scan. These examinations are sometimes useful for the etiological investigation.
Most often, moderate hyperglycemia is asymptomatic. We can sometimes see a slight weight loss (1 to 3 kg) and asthenia, but the patient can feel perfectly well. Diabetic cardial syndrome, which includes polyuropolydipsia, weight loss, hyperphagia, exists only for blood glucose higher than 3 g / l. There is then a significant glycosuria, responsible for osmotic polyuria, leading in turn to polydipsia.

3 - Classification

The essential data for the etiological diagnosis are clinical: age, weight, existence of a ketonuria, family inheritance of diabetes.

1.     Diabetes type 1
   It is remarkable for its sudden onset: cardinal syndrome associating polyuropolydipsia, polyphagia, weight loss and asthenia in a young subject, thinning, with ketonuria associated with glucosuria. A family history is only found in 1 out of 10 cases. It occurs mainly before the age of 20, but has two peaks of incidence around 12 and 40 years of age. It may be associated with other autoimmune diseases (vitiligo, Graves' disease, thyroiditis, Biermer's disease).
2. Type 2 diabetes
   In contrast, it is typically characterized by the fortuitous discovery of hyperglycemia in a person over 40 years of age who is overweight or obese, with overweight abdominal predominance (waist / hip ratio greater than 0.8 at the woman, higher than 0.95 in the man). Most often, there is family inheritance of non-insulin-dependent diabetes. Type 2 diabetes is often associated with essential hypertension and / or hypertriglyceridemia. The diagnosis is most often made during a systematic examination. Indeed, type 2 diabetes is asymptomatic. The delay in diagnosis is about 5 years. Thus, in 20% of cases, there is a complication of diabetes at the time of diagnosis.