Diabetes Type 2: Causes and Characteristics

Diabetes Type 2

• Usually has a later onset
• Characterized by insulin resistance, where target tissues are non-responsive
• Typically milder than Type 1 diabetes
• Associated with diet and lifestyle, particularly obesity
• Incidence is increasing, including in children

Characteristics of Diabetes

• Hyperglycaemia, but usually no ketoacidosis
• Often responds to diet and oral hypoglycaemic agents

Metabolic Pattern in Uncontrolled Diabetes Mellitus

• Resembles that of starvation, but more exaggerated
• Insulin is low in starvation, absent in Type 1 diabetes
• Glucagon acts unopposed, leading to uncontrolled production of ketone bodies
• This important mechanism does not operate in diabetes

Chronic Complications of Diabetes Mellitus

• Microangiopathy: changes in small blood vessels, seen as thickening of basement membrane
• Retinopathy: blindness is 25 times more common in diabetic patients
• Nephropathy: renal failure is 17 times more common
• Neuropathy: postural hypotension, impotence, foot ulcers

Treatment of Diabetes

• Type 1: exogenous insulin by injection

Total Fuel Reserves in the Average Man

• Glycogen: 300g in muscle, 80g in liver, 15g in body fluids
• TAG: 15kg in adipose tissue
• Protein: 6kg in muscle
• Total energy reserve: 697.8MJ

The Fasting (Post-Absorptive) State

• Blood glucose concentrations peak an hour after eating and return to normal by two hours after a meal
• Blood glucose is removed for oxidation or storage
• Concentration of insulin drops and glucagon rises

Metabolism in the Fasting State

• Liver maintains blood glucose concentrations at about 4mM
• Adipose tissue provides the greatest source of energy as TAGs
• Hormone-sensitive lipase is activated by glucagon and adrenaline
• FA are transported to the liver bound to albumin

Glucose Production by the Liver

• The first supplier of blood glucose is liver glycogen
• Gluconeogenesis follows from lactate, glycerol, and amino acids
• After 24 hours of fasting, all blood glucose comes from gluconeogenesis

Fatty Acid Metabolism

• Fatty acids are not gluconeogenic precursors
• The reaction catalyzed by Pyruvate dehydrogenase is irreversible
• PDH is activated by insulin and inhibited by glucagon

Ketone Body Formation

• FA oxidation in the hepatocyte leads to high concentrations of Acetyl CoA
• Acetyl CoA is channelled into ketone body formation
• Acetoacetate and β-hydroxybutyrate are released into the bloodstream

Prolonged Fasting (Starvation)

• If the early pattern were to continue, body protein would be severely depleted
• Only about a third of body protein can be lost without severe or fatal consequences

This quiz covers the characteristics of diabetes type 2, including its onset, symptoms, and treatment options. Learn about insulin resistance, associations with diet and lifestyle, and the metabolic pattern in uncontrolled diabetes.