• Dr. Ratika Rastogi , Physician


Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar (glucose) levels that result from defects in insulin secretion, or its action, or both.


The two types of diabetes are referred to as type 1 and type 2 also known as insulin-dependent and non-insulin-dependent diabetes, or juvenile onset and adult-onset diabetes.


Being overweight or obese, leading a sedentary lifestyle, a family history of diabetes, hypertension (high blood pressure), and low levels of the "good" cholesterol (HDL) and elevated levels of triglycerides in the blood are some of the risk factors.


According to diabetes atlas , the global prevalence of diabetes is estimated at 415 million (8.8%), which is predicted to rise to 642 million in next 25 years. In India, there are about 69.2 million people with diabetes and are expected to cross 123.5 million by 2040. Worldwide, approximately 193 million diabetics remain undiagnosed predisposing them to the development of several long-term complications of untreated chronic hyperglycemia. Although intensive glycemic control lowers the incidence and progression of microvascular complications, the morbidity associated with these complications is still increasing.


The pathologic hallmark of DM involves the vasculature leading to both microvascular and macrovascular complications. Chronicity of hyperglycemia is associated with long-term damage and failure of various organ systems mainly affecting the eyes, nerves, kidneys, and the heart. Chronic elevation of blood glucose level leads to damage of blood vessels called angiopathy. The endothelial cells lining the blood vessels take in more glucose than normal, since they do not depend on insulin. They then form more surface glycoproteins than normal, and cause the basement membrane to grow thicker and weaker. The resulting problems are grouped under "microvascular disease" due to damage to small blood vessels, and "macrovascular disease" due to damage to the arteries.


Diabetic ketoacidosis

DKA is an acute and dangerous complication that whereby low insulin levels cause the liver to turn fatty acid to ketone for fuel (i.e., ketosis) Elevated levels of ketone bodies in the blood decrease the blood's pH, leading to DKA.The patient in DKA is typically dehydrated, and breathing rapidly and deeply. Abdominal pain is common and may be severe. Ketoacidosis can cause hypotension, shock, and death. Ketoacidosis is much more common in type 1 diabetes than type 2.

Hyperglycemic hyperosmolar state

Nonketotic hyperosmolar coma (HNS) is an acute complication where , in a person with very high ( above 300 mg/dl ) 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. Electrolyte imbalances are also common and are always dangerous. It is more common in type 2 diabetes than type 1.


Hypoglycemia, or abnormally low blood glucose, is an acute complication of several diabetes treatments. 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. Consciousness can be altered or even lost in extreme cases, leading to coma, seizures, or even brain damage and death. In most cases, hypoglycemia is treated with sugary drinks or food. In severe cases, an injection of glucagon (a hormone with effects largely opposite to those of insulin) or an intravenous infusion of dextrose is used for treatment .

Diabetic coma

Diabetic coma is a medical emergency in which a person with diabetes mellitus is comatose (unconscious) because of one of the above mentioned acute complications of diabetes .



The damage to small blood vessels leads to a microangiopathy, which can cause one or more of the following:

  • Diabetic nephropathy,damage to the kidney which can lead to chronic kidney disease . Initially, diseased small blood vessels in the kidneys cause the leakage of protein in the urine. Later on, the kidneys lose their ability to cleanse and filter blood. The accumulation of toxic waste products in the blood leads to the need for dialysis. 
    Diabetic neuropathy, is also caused by disease of small blood vessels. In essence, the blood flow to the nerves is limited, leaving the nerves without blood flow, and they get damaged or die . Symptoms of diabetic nerve damage include numbness, burning, and aching of the feet and lower extremities. When the nerve disease causes a complete loss of sensation in the feet, patients may not be aware of injuries to the feet, and fail to properly protect them. Shoes or other protection should be worn as much as possible. Seemingly minor skin injuries should be attended to promptly to avoid serious infections. Because of poor blood circulation, diabetic foot injuries may not heal. Sometimes, minor foot injuries can lead to serious infection, ulcers, and even gangrene, necessitating surgical amputation of toes, feet, and other infected parts. Diabetic nerve damage can affect the nerves that are important for penile erection, causing erectile dysfunction. ED can also be caused by poor blood flow to the penis from diabetic blood vessel disease. Diabetic neuropathy can also affect nerves to the stomach and intestines, causing nausea, weight loss, diarrhea, and other symptoms of gastroparesis (delayed emptying of food contents from the stomach into the intestines, due to ineffective contraction of the stomach muscles).
    Diabetic retinopathyoccurs in patients who have had diabetes for at least five years. Diseased small blood vessels in the back of the eye cause the leakage of protein and blood in the retina. Disease in these blood vessels also causes the formation of small aneurysms (micro aneurysms), and new but brittle blood vessels (neovascularization). Spontaneous bleeding from the new and brittle blood vessels can lead to retinal scarring and retinal detachment, thus impairing vision. Cataracts and glaucoma are also more common among diabetics
    Diabetic encephalopathyis the increased cognitive decline and risk of dementia, including (but not limited to) the Alzheimer's type, observed in diabetes.
    Diabetic cardiomyopathy, damage to the heart muscle, leading to impaired relaxation and filling of the heart with blood (diastolic dysfunction) and eventually heart failure.

  Macrovascular disease

  • Macrovascular disease leads to cardiovascular disease, to which accelerated atherosclerosis is a contributor:

    Coronary artery disease, leading to anginaor myocardial infarction ("heart attack")
    Diabetic myonecrosis('muscle wasting')
    Peripheral vascular disease, which contributes to intermittent claudication(exertion-related leg and foot pain) as well as diabetic foot. Diabetic foot, often due to a combination of sensory neuropathy (numbness or insensitivity) and vascular damage, increases rates of skin ulcers (diabetic foot ulcers) and infection and, in serious cases, necrosis and gangrene. It is why it takes longer for diabetics to heal from leg and foot wounds and why diabetics are prone to leg and foot infections
    Stroke(mainly the ischemic type)
    Female infertilityis more common in women with diabetes type 1, also delayed puberty and menarche, menstrual irregularities (especially oligomenorrhoea), mild hyperandrogenism, polycystic ovarian syndrome, fewer live born children and possibly earlier menopause

 Immune compromise

Immune dysfunction is another major complication and develops from the direct effects of hyperglycemia on cellular immunity. Diabetic patients are particularly susceptible to bacterial and fungal infections.


Prevention is the optimal approach to managing the microvascular complications of diabetes. An aggressive and intensive control of elevated levels of blood sugar in patients with type 1 and type 2 diabetes as well as hypertension decreases the complications of nephropathy, neuropathy, retinopathy, and may reduce the occurrence and severity of large blood vessel diseases. Aggressive control with intensive therapy means achieving fasting glucose levels between 70-120 mg/dl; glucose levels of less than 160 mg/dl after meals; and a near normal hemoglobin A1c levels .


The prognosis of diabetes is related to the extent to which the condition is kept under control to prevent the development of the complications. Some of the more serious complications of diabetes such as kidney failure and cardiovascular disease, diabetic ketoacidosis can also be life-threatening. Aggressive control of blood sugar levels can prevent or delay the onset of complications, and many people with diabetes will be able to lead long and full lives.

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