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Diabetes mellitus. Dr. Essam H. Jiffri. Introduction. - Diabetes mellitus is a heterogeneous group of disorders characterized by hyperglycaemia, glycosuria and associated abnormalities of lipid and protein metabolism.
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Diabetes mellitus Dr. Essam H. Jiffri
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.
Introduction • -Insulin metabolism is abnormal in diabetes, either because of: • reduced secretion or • to 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)
Classification of diabetes mellitus Insulin- Dependent (Type I) Diabetes Non-Insulin- Dependent (Type 2) Diabetes Malnutrition Related Diabetes Mellitus Impaired Glucose Tolerance Secondary Diabetes Gestational Diabetes Mellitus
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.
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 or • mumps.
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.
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: • Obese • Non-obese
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.
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 or • a secretory defect in the pancreatic beta-cells
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.
3- Malnutrition-Related Diabetes Mellitus • -Found mainly in developing countries due to protein-deficient diabetes. • -The aetiology of these is not clear.
4- Diabetes Associated with Other Disorders (Secondary Diabetes) • - Diabetes may occur in association with other conditions, particularly pancreatic disorders such as: • chronic pancreatitis • haemochromatosis may cause destruction of beta-cells.
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 syndrome • Down's syndrome
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.
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).
KEY POINTS Type 1 diabetes mellitus is characterized by insulin deficiency • Type 2 diabetes mellitus is characterized • by insulin resistance • Diabetes mellitus is diagnosed by • clinical features and blood glucose • measurements or an oral glucose tolerance test.