Diabetes Mellitus - Biochemistry

DIAGNOSIS

• Diabetes: fasting blood glucose > 126 mg/dl
• Normal: fasting blood glucose < 100 mg/dl
• Prediabetes: 125 > fasting blood glucose > 100

TYPES OF DIABETES

• Autoimmune destruction of pancreatic beta cells
• Rarer than Type II
• Sudden onset

• Most common type
• Symptoms tend to be milder than Type I
• Gradual onset of symptoms
• Normally insulin-sensitive tissues become insulin resistant

BIOLOGICAL MARKERS OF TYPE I AND TYPE II DIABETES 1. Tissues cannot use glucose (no insulin or insulin resistance) 2. Liver increases gluconeogenesis

• Adipose breaks down TAG to FFA & glycerol (gluconeogenic)
• Skeletal muscle breaks down proteins: releases glucogenic amino acids
• Pancreatic alpha cells secrete abnormally high levels of glucagon

• Adipose breaks down TAG and releases FFA & glycerol
• Liver releases TAG in VLDL
• VLDL & chylomicrons accumulate because of low lipoprotein lipase (LPL) concentrations
• Insulin normally stimulates LPL synthesis

• Increased glucagon secretion promotes ketogenesis
• Adipose FFA shunt into ketogenesis
• Type II diabetics: hyperglycemia & hypertriglyceridemia w/o ketoacidosis

HYPERGLYCEMIA PRESENTATION

• Mass mobilization of adipose TAG & muscle proteins
• Overproduction of glucagon

• Ketoacidosis and hyperglycemia inhibit kidney urine filtration
• Glycosuria (glucose in the urine)
• Ketonuria (ketone bodies in the urine): Type I ONLY
• Leads to extreme thirst

• Extreme conditions: polyuria can lead to volume depletion
• Volume depletion and ketoacidosis can produce diabetic coma