2 Introduction- Diabetes mellitus is a heterogeneous group of disorders characterized by hyperglycaemia, glycosuria and associated abnormalities of lipid and protein metabolism.-It is common, affecting up to 2% of Westem populations, 17% in Saudi Arabia.
3 Introduction-Insulin metabolism is abnormal in diabetes, either because of:reduced secretion orto insensitivity to its effects.-Two main types of Diabetes:Insulin-dependent (IDDM or type 1 diabetes mellitus, formerly juvenile-onset)Non-insulin-dependent (NIDDM or type 2 diabetes mellitus, formerly maturity onset)
4 Classification of diabetes mellitus Insulin-Dependent(Type I)DiabetesNon-Insulin-Dependent(Type 2)DiabetesMalnutritionRelatedDiabetesMellitusImpairedGlucoseToleranceSecondaryDiabetesGestationalDiabetesMellitus
5 1- Insulin- Dependent (Type I) Diabetes -Insulin secretion is absent or severely reduced in IDDM as a result of immunological destruction of beta- cells in the islets of Langerhans.-Circulating islet cell antibodies are found in the majority of patients at presentation and infiltration of the islets by T lymphocytes also occurs.
6 1- Insulin- Dependent (Type I) Diabetes -Genetic factors are important in the development of IDDM-individuals with human leukocyte antigen (HLA) system antigens DR3 and DR4 have increased susceptibility for IDDM.-The environmental event effects, usually a viral infection, particularly with:Coxsackie B4 ormumps.
7 1- Insulin- Dependent (Type I) Diabetes -Most cases of IDDM present before 30 years of age.-The clinical presentation is often acute, with polyuria, polydipsia, polyphagia, weight loss and tiredness developing over several days and ketosis may be present.
8 2-Non-Insulin-Dependent (Type 2) Diabetes -Non-insulin-dependent diabetes is a heterogeneous group of disorders in which several features contrast with those found in IDDM.-NIDDM has been divided by the World Health Organization (WHO) into two main groups:ObeseNon-obese
9 2-Non-Insulin-Dependent (Type 2) Diabetes - Insulin secretion is retained, although it is inadequate to control blood glucose levels.- There is resistance to the effects of insulin in due to reduced insulin receptors-Genetic factors are a more important aetiological factor in NIDDM than IDDM.-Identical twins have a near 100% chance and the risk of developing NIDDM is higher than IDDM if a parent has the disease.
10 2-Non-Insulin-Dependent (Type 2) Diabetes -There are no HLA associations and no islet cell antibodies are found.- Not all patients with NIDDM are over weight, there is a clear association with obesity.- Obese patients develop NIDDM either have:diminished pancreatic reserve ora secretory defect in the pancreatic beta-cells
11 2-Non-Insulin-Dependent (Type 2) Diabetes -Clinical onset is usually in middle age and the prevalence increases with age.- NIDDM is often detected by urine testing during a routine medical examination.- Patients may complain of polyuria and polydipsia, ketosis is rare.
13 3- Malnutrition-Related Diabetes Mellitus -Found mainly in developing countries due to protein-deficient diabetes.-The aetiology of these is not clear.
14 4- Diabetes Associated with Other Disorders (Secondary Diabetes) - Diabetes may occur in association with other conditions, particularly pancreatic disorders such as:chronic pancreatitishaemochromatosis may cause destruction of beta-cells.
15 4- Diabetes Associated with Other Disorders (Secondary Diabetes) -Endocrinopathies (endocrine disorders) which result in:- increased secretion of counter-regulatory hormones can induce insulin resistance.-Diabetes occurs in association with several genetic disorders, including:Turner's syndromeDown's syndrome
16 5- Gestational Diabetes Mellitus - Gestational diabetes occurs for the first time in pregnancy.- Glycosuria is common because the renal threshold for glucose is exceeded.- Complications can occur due to blood glucose concentrations in both mother and fetus.- Glucose tolerance reverts to normal after delivery in most cases many later develop frank diabetes.
17 6- Impaired Glucose Tolerance -Impaired glucose tolerance (IGT) is an asymptomatic condition-Diagnosed on the basis of the response of blood glucose to the ingestion of a standard oral glucose solution (oral glucose tolerance test, OGTT; 75g anhydrous sugar in 300 ml water, blood and urine samples taken at 2h).
18 KEY POINTS Type 1 diabetes mellitus is characterized by insulin deficiencyType 2 diabetes mellitus is characterizedby insulin resistanceDiabetes mellitus is diagnosed byclinical features and blood glucosemeasurements or an oral glucose tolerance test.