What is diabetes mellitus?

Diabetes a group of disorders

What is diabetes mellitus?

Diabetes: An Overview
Diabetes mellitus is a group of disorders of carbohydrate metabolism in which glucose is underused causing hyperglycemia. Diabetes is a common disease.
Types of Diabetes:
• Type 1 Diabetes mellitus
• Type 2 Diabetes mellitus
• Other specific types of Diabetes mellitus
o Gestational Diabetes
o Impaired glucose tolerance
o Impaired fasting glucose

How glucose is controlled in body?

The absorbed glucose after meal is converted to glycogen for storage in liver and skeletal muscles or fat for storage in adipose tissue. During fasting glycogen storage is breakdown to glucose. Some glucose is also derived from gluconeogenesis. Despite large fluctuations in supply and demand of glucose, the concentration of glucose is maintained within a fairly narrow range by hormones. Insulin decreases blood glucose and glucagon, epinephrine, cortisol and growth hormone increases blood glucose concentration.
Normal glucose disposal depends on:
• The ability of pancreas to secrete insulin
• The ability of insulin to promote uptake of glucose
• The ability of insulin to suppress glucose production by liver

What causes diabetes mellitus?

Depending on type, Diabetes mellitus have different causes:
• Causes of Type 1 diabetes mellitus: This is an autoimmune disease. Autoantibodies destroy insulin producing cells in the pancreas. Deficiency of insulin causes uncontrolled rise in glucose. Heredity may also play a role in cases. Viral infections may also trigger the antibodies productions which may cross react with pancreatic beta cells. There occurs deficiency of insulin hormone which has to be given externally for lifelong.
• Cause of Type 2 diabetes mellitus and prediabetes or glucose intolerance: Insulin resistance is the main cause of type 2 diabetes mellitus. Insulin is either normal or may be increased.
• Gestational diabetes mellitus: Hyperglycemia during pregnancy in otherwise normal women is called gestational diabetes mellitus. Pregnancy induced changes in body causes increases resistant to insulin causing gestational diabetes.

What are the risk factors for diabetes mellitus?

Factors that increase risk differ depending on the type of diabetes:
Risk factors for type 1 diabetes mellitus:
• Family history increases the risk of developing type 1 diabetes mellitus.
• Environmental factors such as exposure to viral infections may play some role in type 1 diabetes.
• The presence of autoantibodies increases the risk for type 1 diabetes mellitus.
• Injury to the pancreas such as by infection, tumor, surgery or accident.

Risk factors for Type 2 diabetes mellitus and prediabetes or glucose intolerance:
• Increased weight: Increased fatty tissue increases chances of insulin resistant.
• Physical Inactivity: Regular exercise or physical activates controls the weight and making the tissues more sensitive to insulin. Inactivity causes increased insulin resistance.
• Family history increases the risk for type 2 diabetes mellitus.
• Race or ethnicity: Black, Hispanic, American Indian and Asian American are at higher risk.
• Gestational diabetes: increases the risk of developing Type 2 diabetes mellitus and prediabetes or glucose intolerance later in life.
• Polycystic ovarian syndrome: Women having PCOS are at increases the risk of developing diabetes mellitus.
• Increased cholesterol, triglycerides and low HDL increases the risk.

Risk factors for gestational diabetes mellitus:
• Women older than age 25 years are at increased risk.
• Family history increases risk.
• Over weight before pregnancy increases the risk.

What are the symptoms of diabetes mellitus?

The triad of symptoms is the hallmark of diabetes mellitus:
• Increased thirst (Polydipsia).
• Increased urination (Polyuria)
• Increased appetite (Polyphagia)

Other symptoms of diabetes mellitus are:
• Weakness
• Blurring of vision
• Numbness or tingling sensations in the hands or feet
• Delayed healing
• Unexplained weight loss or weight gain
• Frequent unexplained infections
• Dry mouth
• Frequent fungal infections

What are the complications of diabetes mellitus?

Long term complications of diabetes mellitus develop gradually. The longer the duration and less controlled blood sugar increase the risk of complications. The mechanism for hyperglycemic tissue damage includes:
• Glycation of proteins forming advanced glycation end products (AGEs).
• Overactivity of polyol pathway generating sorbitol that accumulates in cells.
• Generation of reactive oxygen species.

Most common complications are:
• Cardiovascular disease: Diabetes mellitus increases the risk of various cardiovascular complications such as coronary artery disease (CAD), myocardial infarctions, atherosclerosis and stroke.
• Diabetic nephropathy is the most common long term complication of diabetes involving kidneys, the leading cause of ESRD (end stage renal disease/ CKD).
• Diabetic neuropathy: Increased glucose levels can damage nerves especially peripheral nerves. This can cause tingling, numbness, burning sensations or pain that usually begins at the tips of the toes or fingers and gradually spreads upward. If untreated all sensations can be lost.
• Retinopathy: Diabetes can damage the blood vessels of the retina called diabetic retinopathy, can lead to blindness. Diabetes also increases the risk of other cataracts and glaucoma.
• Diabetic foot: Nerve damage in the feet or poor blood flow to the feet increases the risk of injuries followed by nonhealing, serious infections and amputation.
• Infections: Diabetes may increases risk for recurrent bacterial and fungal infections.
• Alzheimer's disease: Diabetes may increase the risk of dementia and Alzheimer's disease.

Complications of gestational diabetes: Gestation diabetes may cause defects/ abnormalities in new born:
• Over weight baby: Extra glucose can cross the placenta which triggers pancreas of fetus to secrete more insulin. This can cause fetus to grow too large called macrosomia.
• Hypoglycemia of newborn: Increased insulin secretion in fetus can cause serious lifethreatening hypoglycemia in newborn.
• Babies of mothers who have gestational diabetes have a greater risk of developing obesity and type 2 diabetes later in life.
• Congenital abnormalities: Babies born to diabetic mother have greater chances of congenital abnormalities such as congenital heart defects (transposition of the great vessels, ventricular septal defects, atrial septal defects, coarctation of the aorta, cardiomyopathy, and single umbilical artery) and central nervous system defects (anencephaly, spina bifida, microcephaly, and holoprosencephaly) renal system (renal agenesis, hydronephrosis, and ureteric abnormalities), cardiovascular system.

What are the complications of diabetes mellitus?

Long term complications of diabetes mellitus develop gradually. The longer the duration and less controlled blood sugar increase the risk of complications. The mechanism for hyperglycemic tissue damage includes:
• Glycation of proteins forming advanced glycation end products (AGEs).
• Overactivity of polyol pathway generating sorbitol that accumulates in cells.
• Generation of reactive oxygen species.

Most common complications are:
• Cardiovascular disease: Diabetes mellitus increases the risk of various cardiovascular complications such as coronary artery disease (CAD), myocardial infarctions, atherosclerosis and stroke.
• Diabetic nephropathy is the most common long term complication of diabetes involving kidneys, the leading cause of ESRD (end stage renal disease/ CKD).
• Diabetic neuropathy: Increased glucose levels can damage nerves especially peripheral nerves. This can cause tingling, numbness, burning sensations or pain that usually begins at the tips of the toes or fingers and gradually spreads upward. If untreated all sensations can be lost.
• Retinopathy: Diabetes can damage the blood vessels of the retina called diabetic retinopathy, can lead to blindness. Diabetes also increases the risk of other cataracts and glaucoma.
• Diabetic foot: Nerve damage in the feet or poor blood flow to the feet increases the risk of injuries followed by nonhealing, serious infections and amputation.
• Infections: Diabetes may increases risk for recurrent bacterial and fungal infections.
• Alzheimer's disease: Diabetes may increase the risk of dementia and Alzheimer's disease.

Complications of gestational diabetes: Gestation diabetes may cause defects/ abnormalities in new born:
• Over weight baby: Extra glucose can cross the placenta which triggers pancreas of fetus to secrete more insulin. This can cause fetus to grow too large called macrosomia.
• Hypoglycemia of newborn: Increased insulin secretion in fetus can cause serious lifethreatening hypoglycemia in newborn.
• Babies of mothers who have gestational diabetes have a greater risk of developing obesity and type 2 diabetes later in life.
• Congenital abnormalities: Babies born to diabetic mother have greater chances of congenital abnormalities such as congenital heart defects (transposition of the great vessels, ventricular septal defects, atrial septal defects, coarctation of the aorta, cardiomyopathy, and single umbilical artery) and central nervous system defects (anencephaly, spina bifida, microcephaly, and holoprosencephaly) renal system (renal agenesis, hydronephrosis, and ureteric abnormalities), cardiovascular system.