Diabetes Mellitus Overview and Causes

Hyperglycemia

• Can be caused by intravenous glucose, severe stress (trauma, heart attack, stroke), diabetes, or impaired glucose regulation.
• Diabetes mellitus results from an absolute or relative lack of insulin.

Diabetes Mellitus (DM)

• Defined by a fasting blood glucose of 7.0 mmol/L or higher (on more than one occasion with symptoms)
• Or a random blood glucose of 11.1 mmol/L or higher.
• Oral glucose tolerance tests (OGTT) may be needed for diagnosis.
• Classified into several types including Type 1, Type 2, other specific types, and gestational diabetes.

Type 1 Diabetes Mellitus (Insulin-Dependent)

• Cause: Destruction of beta cells in the pancreas
• Consequence: Lack of insulin production
• Usually presents during childhood and adolescence
• Requires insulin therapy.
• Can be autoimmune (Type 1A) or with unknown cause (Type 1B)
• Latent autoimmune diabetes of adults (LADA) sometimes considered a slow onset Type 1 diabetes

Type 2 Diabetes Mellitus (Non-Insulin Dependent)

• Insulin resistance with relative insulin deficiency or a secretory defect with insulin resistance.
• Insulin therapy may be needed
• Onset typically during adulthood with a familial tendency and often linked to obesity.

Other Specific Types of Diabetes Mellitus

• Inherited disorders affecting insulin secretion, action, or insulin receptor defects
• Genetic defects of beta-cell function: Maturity-onset diabetes of the young (MODY)
• Genetic defect of insulin action: Type A insulin resistance (insulin receptor defect), for example, leprechaunism, lipoatrophy, and Rabson-Mendenhall syndrome
• Insulin deficiency due to pancreatic disease: Chronic pancreatitis, Pancreatectomy, Haemochromatosis, Cystic fibrosis
• Endocrinopathies: Relative insulin deficiency due to high growth hormone (acromegaly), phaeochromocytoma, or high cortisol (Cushing's Syndrome)
• Drugs: Thiazide diuretics, Interferon alpha, Glucocorticoids
• Infections: Septicaemia, Congenital rubella, Cytomegalovirus
• Rare autoimmune diabetes: Anti-insulin receptor antibodies, Stiff man syndrome (high GAD autoantibodies)
• Genetic syndromes associated with diabetes: Down's syndrome, Turner's syndrome, Klinefelter's syndrome, Myotonic dystrophy.

Gestational Diabetes Mellitus (GDM)

• High risk factors: previous high birth weight delivery , obesity, family history of diabetes, high-risk ethnic groups (Black or South Asian)
• Screen as early as possible and repeat testing at 24-28 weeks
• Diagnosis: Fasting blood glucose ≥ 7.0 mmol/L or random blood glucose ≥ 11.1 mmol/L
• Reclassify after 6 weeks postpartum with repeat OGTT.

Impaired Glucose Tolerance (IGT)

• Fasting blood glucose < 7.0 mmol/L
• Blood glucose between 7.8–11.1 mmol/L two hours after an oral glucose tolerance test (OGTT)
• Some patients with IGT may develop diabetes mellitus later
• Pregnancy IGT is treated as GDM due to the risks to the fetus.

Impaired Fasting Glucose (IFG)

• Similar to IGT, it's an intermediate stage between normal glucose levels and...

This quiz covers the essentials of diabetes mellitus, including its different types, causes such as hyperglycemia, and diagnostic criteria. Explore important aspects of both Type 1 and Type 2 diabetes, along with associated factors like insulin regulation and glucose levels.