Complications of diabetes mellitus
Contents
• Complications of diabetes mellitus
• Pathogenesis of complications of DM
• Oral Glucose Tolerance Test (OGTT)
Objectives
At the end of this PDF Notes, student will be able to
• List the complications associated with DM
• Describe the pathophysiology involved in the
development of diabetic complications
• Describe Oral Glucose Tolerance Test
Clinical features of DM
Type I DM
• Low
plasma insulin levels
• Poly
uria
• Polyphagia
• Polydipsia
• Ketoacidosis
• Hypoglycemic
episodes
Type II DM
• Polyuria
• Polydipsia
• Unexplained
weakness
• Plasma
insulin normal to high
• Hyperosmolar non-ketotic coma
Pathophysiological basis of common signs and symptoms due to uncontrolled hyperglycaemia in diabetes mellitus
Complication of DM – Pathogenesis
• Consequence
of hyperglycemia
• Effects
all most all the tissue
• Complications
can either be acute or chronic
• 2
possible mechanism involved in development of complications
– Non-enzymatic protein glycosylation
– Polyol
pathway mechanism
Non-enzymatic protein glycosylation
• Free
amino group binds reversible to glucose
• Non
enzymatic mechanism
• E.g.
Hb with glucose (glycated Hb)
• Accumulates
on collagen
• Irreversible
advanced glycosylation end products (AGE)
• AGEs
bind to receptors
• Biological & chemical changes
Polyol pathway mechanism
• Intracellular
accumulation of sorbitol & fructose
• Entry
of water inside cell
• Cellular
swelling & damage
• Deficiency
of myo inositol
• Harmful
to retina
Acute metabolic complications
Diabetic ketoacidosis
• Complication
of type I DM
• Due
to shortage of insulin along with glucagon excess
• Failure
to take insulin
• Lipolysis
of adipose tissue
• Free
fatty acids formed taken up by liver
• Converted
ultimately to ketone bodies
• Excreted
in urine
Hype osmolar non-ketotic coma
• Complication
of Type II DM
• Due
to sustained hyperglycemic diuresis
• Loss
of glucose in urine
• Difficult
to substitute the fluids lost of diuresis
• High
viscosity of blood
• Bleeding
complications
• Results
in death
Hypoglycemic episodes
• Complication
of type I & II DM
• Results
from excess administration of insulin or oral hypoglycemic drugs
• May
lead to permanent brain damage
• Worsening
of diabetic control
Late systemic complications
• Atherosclerosis
• Diabetic
microangiopathy
• Diabetic
nephropathy
• Diabetic
neuropathy
• Diabetic
retinopathy
• Infections
Oral Glucose Tolerance Test (OGTT)
• Oral GTT is performed principally
for patients with borderline fasting plasma glucose value (i.e. between 100-140
mg/dl)
• High carbohydrate diet for at least
3 days prior to the test
• overnight fast on the day of the
test
• fasting blood sugar sample is first
drawn
• 75 gm of glucose dissolved in 300 ml
of water is given
• Blood and urine specimen are
collected at half-hourly intervals for at least 2 hours
• Normal cut off value for fasting
blood glucose level -100 mg/dl.
• Fasting blood glucose value in range
of 100- 125 mg/dl - impaired fasting glucose tolerance (IGT)
• Fasting value of plasma glucose
higher than 126 mg/dl
• 2-hour value after 75 gm oral glucose
• Higher than 200 mg/dl - diabetics
Summary
• Persistent
hyperglycemia is associated with diabetic complications
• Non-enzymatic
glycation and polyol pathway mechanism are the two main mechanisms involved in
the development of complications of DM
• Acute
metabolic complication and late systemic complication are major complications
of DM
• Oral GTT is performed principally for patients with borderline fasting plasma glucose value (i.e. between 100-140 mg/dl)
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