Diabetes Mellitus : Causes , Diagnosis and Management

Diabetes Mellitus : Causes , Diagnosis and Management

Diabetes mellitus is a group of metabolic diseases in which the person has high blood glucose (blood sugar) level either due to inadequate insulin production or because the body’s cells do not respond properly to insulin or both. The term “Diabetes Mellitus” describes a metabolic disorder of multiple etiology characterized by chronic hyperglycemia with disturbances of carbohydrate, fat (dyslipidaemia) and protein metabolism resulting from defects in insulin secretion, insulin action, or both. The main symptoms are: –

  1. Polyuria (frequent urination)
  2. Polydipsia (increased thirst)
  3. Polyphagia (increased hunger

The main types of diabetes are:

Type 1 diabetes: It is due to the body’s malfunction to produce insulin in the body, and requires the person to inject insulin. This form was previously referred to as “Insulin-Dependent Diabetes Mellitus” (IDDM) or “Juvenile Diabetes”.

Type 2 diabetes: It is due to insulin resistance, a condition in which cells fail to use insulin properly, sometimes combined with an absolute insulin deficiency. This form was previously referred to as non insulin-dependent diabetes mellitus (NIDDM) or “adult-onset diabetes”.

Type 2 diabetes can be prevented after following healthy life style such as healthy diet, proper exercise or maintaining healthy weight.

The third main form, Gestational diabetes occurs when pregnant women without a previous diagnosis of diabetes develop a high blood glucose level. It may lead to type 2 DM.

Other types of diabetes include those caused by:

  • Genetic defects of the beta cells, (the part of the pancreas that makes insulin) such as maturity-onset diabetes of the young (MODY) or neonatal diabetes mellitus (NDM)
  • Diseases of the pancreas or conditions that damage the pancreas, such as pancreatitis and cystic fibrosis
  • Excess amounts of certain hormones resulting from some medical conditions such as cortisol in Cushing’s syndrome that work against the action of insulin
  • Medications that reduce insulin action, such as glucocorticoids, or chemicals that destroy beta cells


The main symptoms of diabetes are:

  • Polyuria: urinating frequently (particularly at night)
  • Polydipsia: feeling very thirsty
  • Polyphagia: feeling hungry frequently
  • Weakness
  • Weight loss and loss of muscle bulk
  • Frequent episodes of thrush
  • Cuts or wounds that heal slowly
  • Blurred vision

Type 1 diabetes can develop quickly, over weeks or even days. Many people have type 2 diabetes for years without realizing because early symptoms tend to be common.


Type 1 Diabetes: The immune system of body attacks and destroys the cells that produce insulin. As no insulin is produced, glucose levels further increase, which can seriously damage the body’s organs. Type 1 diabetes is often known as insulin-dependent diabetes. It is also sometimes known as juvenile diabetes or early-onset diabetes because it usually develops before the age of 40, often during the teenage years. Type 1 diabetes is less common than type 2 diabetes.

Type 2 Diabetes: Type 2 diabetes is where the body does not produce enough insulin or the body’s cells do not respond to insulin. This is known as insulin resistance. Type 2 diabetes, and is far more common than type 1 diabetes.

Risk factors for type 2 diabetes:

  • Obesity or being overweight
  • Impaired glucose tolerance
  • High blood pressure
  • Dyslipidemia – Low levels of high-density lipoproteins (HDL) (“good”) cholesterol and high levels of triglycerides, high low-density lipoproteins (LDL)
  • Gestational diabetes
  • Sedentary lifestyle
  • Family history
  • Age

Gestational Diabetes: Some women tend to experience high levels of blood glucose as during pregnancy due  to reduced sensitivity of insulin receptors.


The clinical diagnosis of diabetics is often prompted by symptoms such as increased thirst and urination and recurrent infections.

Blood Tests – Fasting plasma glucose, two-hour postprandial test and oral glucose tolerance test are done to know blood glucose levels.

Glycated Haemoglobin (HbA1c) may be used to diagnose diabetes(if facilities are easily available).

Diabetes can be diagnosed by blood glucose and HBA1c levels:

Diabetes diagnostic criteria
Condition 2 hour* plasma glucose Fasting plasma glucose HbA1c
mmol/l(mg/dl) mmol/l(mg/dl) %
Normal <7.8 (<140) <6.1 (<110) <6.0
Impaired Fasting Glucose <7.8 (<140) ≥ 6.1(≥110) & <7.0(<126) 6.0–6.4
Impaired Glucose Tolerance ≥7.8 (≥140) <7.0 (<126) 6.0–6.4
Diabetes mellitus ≥11.1 (≥200) ≥7.0 (≥126) ≥6.5
*Venous plasma glucose 2 hours after ingestion of 75g oral glucose load.
Other tests –
  • Fasting lipid profile, including total, LDL, and HDL cholesterol and triglycerides
  • Liver function tests
  • Kidney function tests
  • Thyroid stimulating hormone (TSH) in type 1 diabetes, dyslipidemia, or women over 50 years of age.


Currently, six classes of oral antidiabetic drugs (OADs) are available: biguanides (e.g., metformin), sulfonylureas (e.g., glimepiride), meglitinides (e.g., repaglinide), thiazolidinediones (e.g., pioglitazone), dipeptidyl peptidase IV inhibitors (e.g., sitagliptin), and α-glucosidase inhibitors (e.g., acarbose).


  • Insulin: Type 1 diabetes is generally treated with combinations of regular and NPH (neutral protamine Hagedorn) insulin or synthetic insulin analogs. When insulin is used in type 2 diabetes, a long-acting formulation is usually added initially while continuing oral medications.
  • Treatment of coexisting medical conditions (high blood pressure, dyslipidemia etc.)
Lifestyle measures
  • Regular exercise
  • Proper diet
  • No smoking
  • No alcohol
These goals help in keeping both short-term and long-term blood glucose levels within acceptable limits.


The complications of diabetes mellitus are less common and less severe in people who have well-controlled blood sugar levels. Its complications are:


  1. Diabetic ketoacidosis (DKA): It is an intense and dangerous complication that can always result in a medical emergency. It is generally seen due to low insulin levels which may cause the liver to turn fatty acid to ketone for fuel as ketone bodies are intermediate substrates in that metabolic sequence. This is a normal condition if occurs periodically, but can become a serious problem if sustained. Elevated levels of ketone bodies in the blood decrease the blood’s pH leading to DKA. The patient with DKA is typically dehydrated and breathing rapidly and deeply. Abdominal pain is common and may be severe.
  2. Hyperglycemia: Hyperglycemia is another acute complication. If a person has very high (usually considered to be above 300 mg/dl (16 mmol/L)) blood glucose levels, water is osmotically drawn out of cells into the blood and the kidneys eventually begin to dump glucose into the urine. This results in loss of water and an increase in blood osmolarity. If fluid is not replaced (by mouth or intravenously) the osmotic effect of high glucose levels combined with the loss of water will eventually lead to dehydration. The body’s cells become progressively dehydrated as water is taken from them and excreted. Electrolyte imbalances are also common and can be very dangerous.
  3. Hypoglycemia: Hypoglycemia or abnormally low blood glucose is an acute complication of several diabetes treatments. It is rare otherwise, either in diabetic or non-diabetic patients. The patient may become agitated, sweaty, weak, and have many symptoms of sympathetic activation of the autonomic nervous system resulting in feelings akin to dread and immobilized panic.
  4. Diabetic Coma: Diabetic coma is a medical emergency in which a person with diabetes mellitus is unconscious as of one of the acute complications of diabetes:
  • Severe diabetic hypoglycemia
  • Diabetic ketoacidosis advanced enough to result in unconsciousness from a combination of severe hyperglycemia, dehydration and shock and exhaustion
  • Hyperosmolar nonketotic coma in which extreme hyperglycemia and dehydration alone are sufficient to cause unconsciousness.


(a)Micro vascular diseases (due to damage to small blood vessels):

1.     Eye Diseases:

  • Retinopathy (nonproliferative/proliferative)
  • Macular oedema

These conditions can lead to serious vision loss or blindness.

2.     Neuropathy:

  • Sensory and motor(mono-and polyneuoropathy) neuropathy: sensory symptoms such as  tingling , burning, stabbing pain or other abnormal sensations and motor symptoms such as sensory loss, weakness, numbness starting from feet and later on can involve finger and arm.
  • Autonomic neuropathy affects the digestive system, blood vessels, urinary system as well as sex organs.

3.     Nephropathy: Damage to kidney can lead to chronic renal failure.

(b) Macro vascular diseases:

  • Coronary artery  disease
  • Peripheral arterial disease
  • Cerebrovascular disease

(c) Other diseases:

  • High blood sugar level in blood can lead to cataract, glaucoma.
  • Dermatological complications- bacterial infections, fungal infections and some other skin conditions are more common in diabetic persons.
  •  Infectious diseases are more frequent and/or serious in patients with diabetes mellitus.
  • Periodontal Disease-When diabetes is not controlled properly high glucose levels in mouth fluids may help germs to develop and cause periodontal diseases.
  • Cheiroarthropathy is a condition of limited joint mobility in patients with diabetes and is characterized by thickening of the skin resulting in contracture of the fingers.
  • Diabetic dyslipidemia: The characteristic features are a high plasma triglyceride concentration, low high density liprotein (HDL) concentration and increased concentration of low density lipoproteins (LDL).

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