Diabetes Mellitus


Updated 4 March 2021

Diabetes mellitus (DM) is a group of metabolic disorders characterized by hyperglycemia and abnormalities in carbohydrate, fat, and protein metabolism. 

Type 1 DM (5%–10% of cases) usually develops in childhood or early adulthood and results from autoimmune-mediated destruction of pancreatic β-cells, resulting in absolute deficiency of insulin. The autoimmune process is mediated by macrophages and T lymphocytes with autoantibodies to β-cell antigens (eg, islet cell antibody, insulin antibodies).

Diabetes is classified into three types namely Type 1, Type 2 and Gestational Diabetes.

Type 1 diabetes: Body does not produce insulin at all. People with this form of diabetes require daily injections of insulin in order to control the levels of glucose in their blood.

Type 2 diabetes: This is the most common type of diabetes. The body produces some insulin, but not enough. This type of diabetes used to be seen only in adults but it is now also occurring increasingly in children and adolescents. It is seen in those with a family history of diabetes, excess body weight, lack of physical activity, and as people grow older.

Gestational diabetes: Diabetes which occurs among women during pregnancy. Has a risk of complications during pregnancy and delivery. The children of women with Gestational Diabetes are at an increased risk of type 2 diabetes in the future.

Type 1 diabetes mellitus

Type 2 DM (90% of cases) is characterized by a combination of some degree of insulin resistance and relative insulin deficiency. Insulin resistance is manifested by increased lipolysis and free fatty acid production, increased hepatic glucose production, and decreased skeletal muscle uptake of glucose.

• Uncommon causes of diabetes (1%–2% of cases) include endocrine disorders (eg, acromegaly, Cushing syndrome), gestational diabetes mellitus (GDM), diseases of the exocrine pancreas (eg, pancreatitis), and medications (eg, glucocorticoids, pentamidine, niacin, α-interferon).

• Microvascular complications include retinopathy, neuropathy, and nephropathy. Macrovascular complications include coronary heart disease, stroke, and peripheral vascular disease.

Clinical presentation of type 1 diabetes melitus

• The most common initial symptoms are polyuria, polydipsia, polyphagia, weight loss, and lethargy accompanied by hyperglycemia.

• Individuals are often thin and are prone to develop diabetic ketoacidosis if insulin is withheld or under conditions of severe stress.

• Between 20% and 40% of patients present with diabetic ketoacidosis after several days of polyuria, polydipsia, polyphagia, and weight loss.

Risk Factors for Type 2 Diabetes

• Family history of diabetes.

• It occurs most frequently in adults, but is seen increasingly in adolescents as well.

• Being overweight.

• Unhealthy eating habits.

• Lack of physical activity.

• High blood pressure.

• High levels of harmful blood fats.

• Addictions like tobacco use, drug and harmful use of alcohol.

• If the woman during pregnancy had diabetes or even mild elevation of blood sugar level during pregnancy.

Common Signs and Symptoms of Type 2 Diabetes

• Frequent urination.

• Increased hunger.

• Excessive thirst.

• Unexplained Weight loss.

• Lack of energy, extreme tiredness.

• Blurred vision.

• Repeated or severe infections such as vaginal infections.

• Slow healing of wounds.

If the blood glucose stays too high, it can cause damage to the

• Kidneys – causing kidney failure.

• Heart and blood vessel disease – causing heart attack and stroke.

• Nerves damage – causing numbness, tingling in hands and/or feet, foot ulcers and infections.

• Eyes – causing blindness.

• Oral cavity – causing gum diseases.


Criteria for diagnosis of DM include any one of the following:  

1. A1C of 6.5% or more

2. Fasting (no caloric intake for at least 8 hours) plasma glucose of 126 mg/dL (7.0 mmol/L) or more

3. Two-hour plasma glucose of 200 mg/dL (11.1 mmol/L) or more during an oral glucose tolerance test (OGTT) using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water

4. Random plasma glucose concentration of 200 mg/dL (11.1 mmol/L) or more with classic symptoms of hyperglycemia or hyperglycemic crisis In the absence of unequivocal hyperglycemia, criteria 1 through 3 should be confirmed by repeat testing.


• Normal fasting plasma glucose (FPG) is less than 100 mg/dL (5.6 mmol/L).
• Impaired fasting glucose (IFG) is FPG 100 to 125 mg/dL (5.6–6.9 mmol/L).
• Impaired glucose tolerance (IGT) is diagnosed when the 2-hour postload sample of OGTT is 140 to 199 mg per dL (7.8–11.0 mmol/L)

• Pregnant women should undergo risk assessment for GDM at first prenatal visit and have glucose testing if at high risk (eg, positive family history, personal history of GDM, marked obesity, or member of a high-risk ethnic group).

Blood Glucose Estimation

A glucometer is a device used to determine glucose levels in the blood. It enables a blood glucose check using a small drop of blood. For the purposes of screening, any patient with a random blood sugar over 140 mg/dl should be referred to the medical officer for further investigation.

Blood glucose estimation using a glucometer


• Cotton (dry or with spirit); swab.

• Lancet (needle).

• Lancet device (pricker).

• Test strips.

• Glucometer.

• Sharp bin.

• Alcohol based wipe.

Process steps

1. Wash your hands to prevent infection.

2. Ask the participant to wash and dry their hands thoroughly.

3. Place the glucometer on a flat surface.

4. Open the lancet device provided with the glucometer.

5. Insert the lancet. Take the sealing cap off the needle. Do not touch the needle. Close the device. Set the spring of the device so that it is ready to use by pressing or pulling the load button on the lancet device.

6. Clean the fingertip of the subject prior to needle prick.

7. Turn on the glucometer and place a test strip in the machine when the machine is ready. One end will need to face the top of the glucometer; usually it has a dark coloured line on it. This is where the blood will be placed for testing. Watch the indicator for indication to place a blood drop onto the strip.

8. Use a lancet to prick the side or top of the finger to get small amount of blood. Let the blood flow freely from the fingertip; do not squeeze the finger. Squeezing the finger can affect the results. Rubbing/Milking your finger before pricking it helps in easy availability of a blood droplet for the meter. 

9. Place the drop of blood on the test strip. The blood drop is to be placed against the edge or top of the strip. Wipe away the first drop of blood because it may be contaminated with tissue fluid or debris.

10. Apply cotton ball to subject’s finger and hold firmly until bleeding stops.

11. Watch the glucometer screen. It should show a “waiting” or “processing” symbol, and will produce a beep when the sample has been tested. The results will be displayed as a number on the screen.

12. Note the reading in the notebook or family folder of the subject. Keeping a record will make it easier to identify the subjects who need referral, and for the doctor to establish a good treatment plan.

13. Turn the glucometer off.

14. Place the used needle device into the sharps bin immediately.

15. Dispose of test strip into clinical waste bin before removing gloves.

16. If sharp bin and clinical waste bin are not available; then use two separate boxes to store the sharp disposal and clinical waste products separately. After the blood glucose test; these boxes need to be transferred to bio-hazard container. Always wear gloves before transferring the bio-hazard products. (Be alert to avoid needle pricks).

17. Use an alcohol based wipe to clean the meter ensuring all external surfaces are clean.

18. If the reading is high, then the individual should be referred to a medical professional for check-up.

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