Definition and Types of Diabetes Mellitus

Definition and types of Diabetes Mellitus 

 
Definition
Diabetes occurs either because of a lack of insulin or because of the presence of factors that oppose the action of insulin. The result of insufficient action of insulin is an increase in blood concentration of glucosa . Many other metabolic abnormalities occur, notably an increase in ketone bodies in the blood when there is a severe lack of insulin.
Diagnosis
The diagnosis of diabetes must always be established by a blood glucose measurement made in an accredited laboratory.
Glucose tolerance test
The glucose tolerance test is not normally needed in routine clinical practice, and then only if uncertainty exists in younger patients, or to establish an exact diagnosis in pregnancy. For reliable results, glucose tolerance tests should be performed in the morning after an overnight fast, with the patient sitting quietly and not smoking; it is also mportant that the patient should have normal meals for the previous three days and should not have been dieting. False results may also occur if the patient has been ill recently or has had prolonged bed rest. Blood glucose concentrations are measured fasting and then one and two hours after a drink of 75 g of glucose in 250-350 ml water (in children 1·75 g/kg to a maximum of 75 g), preferably
flavoured, for example, with pure lemon juice. Urine tests should be performed before the glucose drink and at one and two hours. Interpretation of blood glucose values according to WHO criteria is shown in the table. Gestational polygenic disease This term embraces the factors for each polygenic disease and impaired aldohexose tolerance once discovered throughout physiological state Glucose tolerance tests may additionally  show: Renal symptom—this happens once there's glycosuria however normal glucose concentrations; this can be a benign condition, solely seldom indicating uncommon varieties of urinary organ malady. It is price supply these patients with a certificate to forestall them from being subjected to continual aldohexose tolerance tests at each health check. Steeple or lag curve—this is delineated  once abstinence and 2 hour concentrations ar traditional, however those between ar high, causing glycosuria; this can be additionally a benign condition, that most typically occurs when surgical operation however could occur in healthy folks. Impaired aldohexose tolerance This is outlined within the table. Patients ar managed at the discretion of the MD. In general, no treatment is given to
Types of Diabetes disease
Type one Diabetes disease (previously hormone dependent diabetes) is due to B-cell destruction, typically resulting in absolute hormone deficiency). It will be immune mediate or upset. Type a pair of polygenic disease (previously non-insulin dependent diabetes) ranges from those with predominant hormone resistance related to relative hormone deficiency, to those with a preponderantly hormone humor defect with hormone resistance.
Type one and kind a pair of polygenic disease ar the most common sorts of primary DM. The division is vital each clinically in assessing the necessity for treatment, and additionally in understanding the causes of polygenic disease that ar entirely different within the 2 teams.
Type one Diabetes disease
Type one Diabetes disease is attributable to destruction of B-cells within the pancreatic islets of Langerhans with ensuing loss of hormone production. a mixture of environmental and genetic factors that trigger associate degree reaction attack on the B-cells is responsible, occurring in genetically prone people. Thus, among monozygotic identical twins solely concerning tierce of the pairs ar concordant for polygenic disease in distinction to the situation in sort a pair of polygenic disease wherever the majority pairs ar concordant. the method of isle destruction most likely begins very early in life and is thought to begin many years before the clinical onset of polygenic disease.

Associated reaction disorders
The incidence of cavum illness, Addison’s illness, hypothyroidism, and anaemia ar accumulated in Type one diabetic patients, and seem to occur particularly in those with dogging isle cell antibodies.
Risks of inheritable  polygenic disorder
A child of a mother with kind one polygenic disorder has associate degree accumulated risk of developing identical variety of polygenic disorder, amounting to 1-2% by twenty five years; the danger is regarding thrice larger if the father has this illness. If each folks have the illness the danger is more accumulated and genetic guidance ought to be wanted by these rare couples.

Type 2 diabetes
There are numerous causes of Type 2 diabetes, which is now known to include a wide range of disorders with differing progression and outlook. The underlying mechanism is due either to diminished insulin secretion—that is, an islet defect, associated with increased peripheral resistance to the action of insulin resulting in decreased peripheral glucose uptake, or increased hepatic glucose output. Probably as many as 98% of Type 2 diabetic patients are “idiopathic”—that is, no specific causative defect has been identified. Whether decreasing insulin secretion or increasing insulin resistance occurs first is still uncertain, but the sequence of events may vary in different individuals. Obesity is the commonest cause of insulin resistance. Other rare insulin resistant states are shown in the table. Some adults (especially those not overweight) over 25 years of age who appear to present with Type 2 diabetes may have latent autoimmune diabetes of adulthood (LADA) and become insulin dependent. Autoantibodies are often present in this group of patients.
Type 2 diabetes is a slowly progressive disease: insulin secretion declines over several decades, resulting in an insidious deterioration of glycaemic control which becomes increasingly difficult to achieve.
Obesity
Relative insulin resistance occurs in obese subjects, perhaps because of down regulation of insulin receptors due to hyperinsulinaemia. Obese subjects have a considerably increased risk of developing Type 2 diabetes. Fat distribution is relevant to the development of diabetes, so that those who are “apple shaped” (android obesity, waist-hip ratio 0·9) are more prone to Type 2 diabetes than those who are “pear shaped” (gynoid obesity, waist-hip ratio 0·7).
The importance of leptin in the evolution of lifestyle related obesity is unclear. Leptin is a single chain peptide produced by adipose tissue and its receptors are expressed widely throughout the brain and peripheral tissues; when injected into leptin deficient rodents it causes profound hypophagia and weight loss. Plasma leptin levels rise in parallel with body fat content. Although very rare cases of morbid obesity due to leptin deficiency have been reported, and are shown to respond to leptin injections, there is in general an absence of measurable biological responses to leptin, which at present has no role in the management of obesity.
Birthweight and sort two polygenic disorder
Recent observations recommend a relationship between low birthweight and therefore the development in time of life of internal secretion resistance, kind two polygenic disorder, and arteria coronaria sickness. Those
who square measure smallest at birth and largest at one year old-time square measure most at risk.
Genetics of kind two polygenic disorder
Type two polygenic disorder incorporates a robust genetic element, manifest in the high concordance of polygenic disorder in monozygotic twins, familial agglomeration and variations in prevalence between ethnic teams. associate degree increasing variety of specific genetic defects have become recognised and a few square measure delineate below.
Type two polygenic disorder in youngsters and teens Hitherto, childhood polygenic disorder was witnessed in some ethnic minorities and in those with the rare hereditary MODY syndromes delineate below. Growing recognition currently exists of a substantial increase of this sickness within the prosperous industrialised nations. within the u.  s., between V-E Day and 45% of recently diagnosed cases of polygenic disorder among youngsters and adolescents square measure kind two, and therefore the drawback is increasing. It is possibly to occur at twelve to fourteen years old-time, more frequently in ladies, and is powerfully related to avoirdupois, physical inactivity and a case history of kind two polygenic disorder. When teens of lean physique square measure discovered to own
Type two polygenic disorder, it's vital to aim to spot whether or not they may represent those with LADA and so in want of insulin. there's additionally proof that in about one-quarter of such patients polygenic disorder is as a result of a specific hereditary disease as well as those of the MODY cluster described below or different rare genetic syndromes. Dominantly hereditary kind two polygenic disorder (MODY) Seven genetic syndromes, 3 of that square measure shown within the box at the highest of page two, cause MODY—defined as associate degree early onset of dominantly hereditary kind two polygenic disorder. 2 (or at the very least one) members of such families ought to are
diagnosed before twenty five years old-time, 3 generations (usually first-degree) ought to have polygenic disorder, and that they mustn't normally need internal secretion till they need had polygenic disorder for a lot of than 5 years.
Mitochondrial polygenic disorder
Mitochondrial polygenic disorder and hearing impairment may be a rare style of polygenic disorder maternally transmitted, and is said to the A3243G mitochondrial desoxyribonucleic acid mutation. polygenic disorder is diagnosed within the fourth to fifth decades, typically in skinny patients with symptoms. Patients respond higher to sulphonylureas than to diet alone. Diabetic microvascular complications do occur. Insulin resistant polygenic disorder Some rare internal secretion resistant states exist within which a whole bunch or
even thousands of units of internal secretion is also ineffective. They are often related to lipodystrophy, lipidemia, and acanthosis nigricans. blood group internal secretion resistance is as a result of genetic defects within the internal secretion receptor or within the post-receptor pathway. Type B internal secretion resistance happens as a results of immunoglobulin autoantibodies directed against the internal secretion receptor; it's often related to different response disorders lik systemic lupus erythematosis, and it's abundant common man in women of African descent. Management of those conditions can be terribly tough and specialist texts ought to be consulted.
Increased risk for Type 2 diabetes
• People over 40 years of age
• People of Asian or African-Caribbean ethnic origin
• Overweight people
• Family history of diabetes
• History of gestational diabetes
• History of large baby (birth weight exceeding 4 kg)