3. Glucose and Diabetes :
Diabetes mellitus is a metabolic disorder. It is characterized by hyperglycemia that leads to several long term complications. Diabetes mellitus is broadly divided into 2 groups, namely insulin-dependent diabetes mellitus (IDDM or TypeI - caused by destruction of β-cells of pancreas by drugs, viruses or autoimmunity) and non-insulin dependent diabetes mellitus (NIDDM or Type II - genetic or environmental). This classification is mainly based on the requirement of insulin for treatment.
IDDM accounts for about 10 to 20% of the known diabetics. Patients of IDDM require insulin therapy. NIDDM accounts for 80 to 90% of the diabetic population. NIDDM occurs in adults (usually above 35 years) and is less severe than IDDM. The patients of NIDDM may have either normal or even increased insulin levels.
Diabetes mellitus is associated with several metabolic alterations. Most important among them are hyperglycemia, ketoacidosis and hypertriglyceridemia. High concentrations of glucose can be harmful causing osmotic effects/hypertcnic effects (water drawn from cells into extracellular fluid and excreted into urine, resulting in dehydration), β-cell damage by free radicals (due to enhanced oxidative phosphorylation, oxidative stress, and increased free radicals) and glycation of proteins (associated with djabetic complicationsneuropathy, nephropathy, retinopathy etc.). Increased mobilization of fatty acids results in overproduction of ketone bodies which often leads to ketoacidosis. Conversion of fatty acids to triacylglycerols and the secretion of VLDL and chylomicrons is comparatively higher in diabetics. Further, the activity of the enzyme lipoprotein lipase - is low in diabetic patients. Consequently, the plasma levels of VLDL, chylomicrons and triacylglycerols are increased. Hypercholesterolemia is also frequently seen in diabetics.
Excretion of glucose in urine is known as glycosuria. Since the most common cause of glucose excretion in urine (glycosuria) is diabetes mellitus, glycosuria is the first line screening test for diabetes. Normally, glucose does not appear in urine until the plasma glucose concentration exceeds renal threshold (180 mg/dl). As age advances, renal threshold for glucose increases marginally.
In case of suspected diabetes mellitus, a request for estimation of serum glucose is made.
