How dangerous is diabetes and what are its complications?
Uncontrolled diabetes is known to affect vital body functions by damaging blood vessels and nerves. Since the kidneys, heart and eyes have a similar kind of blood flow mechanism (all these have ‘bottlenecks’ that can affect the blood flow adversely), these organs are the most affected in individuals with diabetes. The eyes are especially prone to serious damage since they do not have any “parallel blood vessels” (collaterals or bypasses) that are usually present (or may be produced by the body) in case of blood vessel narrowing in the kidneys and heart.
- A. Complications include :
Loss of Vision
- Heart Disease
- Nerve Damage
- Kidney Damage
- Pain in calf muscles
- Gum Problems
- Foot Ulcers
B. What causes complications in diabetes ?
C. Diabetes Control and Complications Trial (DCCT)
I. Loss of vision : Vision tends to deteriorate in diabetes mainly due to two reasons:
Premature formation of cataract : Diabetics have to go in for a frequent change in glasses due to fluctuating vision, which could be due to osmotic changes in the lens of the eye. Moreover, diabetes is an important cause of cataract (opacity in the lens) occurring prematurely. This happens mainly due to Sorbitol. In individuals with diabetes, Sorbitol accumulates in the lens and pulls water into the lens osmotically, making it opaque. The treatment involves removal (extraction) of cataract; once the blood glucose levels are controlled.
Retinal damage or Retinopathy : The other important cause of frequent change in glasses is due to retinal damage (diabetic retinopathy). It occurs more commonly in Insulin Dependent Diabetes Mellitus (IDDM) after about 15 years of having Diabetes.
Retinopathy starts with small dilations, (known as microaneurysms) in the blood vessels in the retina. These microaneurysms grow till a particular limit after which they burst, giving rise to tiny particulate matter (known as exudates) and retinal edema (swelling). As the natural process of compensating for the lost vessel sets off, more and more blood vessel offshoots grow, blocking the light and further diminishing the eyesight. Macula, part of the retina where vision is the best, may also be damaged leading to blindness.
Since vision loss is painless and gradual, it is imperative to diagnose and treat this condition at the earliest stage. Therefore, early detection (through Fundoscopy at least once a year) and appropriate treatment through Photocoagulation laser therapy (which will help to seal the damaged retinal blood vessels) at the right time are essential. In advanced stages, Vitrectomy may be helpful.
II. Heart diseases : The heart is supplied by a distinct set of blood vessels called Coronary arteries. In Diabetes, these arteries are more likely to become the seat for deposition of lipid (fat) particles. This process of deposition of fat particles resulting in thickening and narrowing of arteries is known as atherosclerosis. This could hamper blood flow to the heart muscles and may manifest in the form of chest pain (angina or heart attack).
In long standing Diabetes, many individuals may not feel any pain (due to nerve damage) in the chest during angina or heart attack (known as silent angina/heart attack). Therefore, all diabetics must have a routine ECG and Treadmill test (TMT) done for early detection of Coronary heart disease.
The incidence of heart related problems is 40% greater in patients with Diabetic kidney disease, partly because of associated high blood pressure. Hence, blood pressure should also be monitored frequently in diabetics.
The risk of heart disease may be greater if the individual:
- is hypertensive (high Blood Pressure)
- has abnormal lipid profile
- is obese (over weight)
- has family history of premature coronary heart disease (<55 years)
- is in the post-menopausal age group.
- leads a sedentary life
Recently, research has shown the role of following risk factors to be significant in causation of heat disease in Diabetes:
Chronic inflammation can be detected by measuring the Interleukin IL6 and serum C Reactive Protein (CRP) levels which are linked to insulin resistance. Higher levels of CRP also predicts long-term mortality in unstable heart disease.
Sleep disordered breathing (sleep apnea syndrome) is characterized by severe snoring and temporary stoppage of breathing during sleep. This condition is more common in people with high blood pressure, overweight individuals and older adults.
- Genetic susceptibility to diabetes associated vascular damage. Individuals homozygous for haptoglobin alleles are protected against retinopathy (eye damage), nephropathy (kidney damage) and cardiac damage in diabetes
- Increased homocysteine levels in blood
- Repeated respiratory infections by Chlamydia pneumonia
- Advanced glycation end products (AGEs) are toxic chemicals, which causes the arterial wall to lose its elasticity. High blood sugar levels in diabetics offer more opportunity for the generation of AGEs. This may cause hardening of arteries allowing deposition of fats, which ultimately results in blocking of arteries and related problems.
III. Nerve damage (peripheral neuropathy and autonomic neuropathy) Of all the chronic consequences of diabetes, nerve damage (or neuropathy) is a troublesome feature that may occur early. The severity and frequency of nerve damage tends to increase with severity of hyperglycemia (increased blood glucose levels).
- Peripheral Neuropathy : Although any nerve, anywhere in the body could be involved but the most commonly affected are those in the lower limbs. The sensations or the feelings may be variously described as pins and needles, burning sensation, tingling, numbness and pain, which may become very severe, especially at night. Because feet may also be commonly involved, foot care becomes of paramount importance in diabetes patients.
- Management is directed at normalizing blood glucose levels. To control the pain of neuropathy or nerve damage in Diabetes vitamin E, vitamin B1 (multivitamins), gammalinolenic acid supplements may be prescribed. In certain cases carbamazepine, amitryptiline, fluphenazine or gabapentin may also be used to control pain.
- Autonomic Neuropathy : Damage to the autonomic nerves (nerves supplying internal organs) may affect the function of gastro-intestinal tract, genito-urinary organs and the cardiovascular system predominantly.The most distressing and common problems include:
- Diabetic diarrhea: Episodes of unexplained diarrhea without any crampy pain may appear suddenly (i.e. almost involuntarily) in long standing cases of Diabetes. In addition to control of blood glucose levels, antimotility drugs (Diphenoxylate), tetracycline or clonidine may be prescribed.
- Diabetic Gastroparesis: Delayed emptying of food from stomach may lead to early satiety and can cause nausea and vomiting. Frequent small meals (including liquid diet and low fat diet) may be effective in managing such cases. Domperidone, Metoclopramide or Cisapride can also be prescribed to promote gastric emptying.
- Genito-urinary neuropathy: Inability to hold urine or incomplete evacuation of bladder is a common manifestation which is seen when the nerve supply to the urinary bladder gets affected in long standing diabetes. Infections are fairly common due to residual collection of urine in the bladder. This may cause frequent episodes of burning during urination and discomfort in lower abdomen (pelvic region). Urine culture to find out the offending organism (usually E.coli) and appropriate antibiotics are required in such cases.
- Cardiovascular neuropathy: Feeling of dizziness on suddenly getting up from the bed (postural hypotension) is a distressing feature especially in elderly Diabetic population. For this reason your blood pressure needs to be checked in a sitting and standing posture as well. A decrease of 25 mmHg in systolic blood pressure or 10 mmHg in diastolic blood pressure (after 2 minutes of upright posture) without a compensatory increase in heart rate is indicative of this condition (postural hypotension). Following guidelines may be helpful:
- Wear stockings or tight fitting clothes
- High salt diet may be taken as per medical advice
- Steroids such as Fludocortisone may also be advised
IV. Kidney damage (referred to as diabetic nephropathy) : Diabetes associated kidney disease (Diabetic nephropathy) is a serious complication of long-term diabetes. Statistics indicate that 40% of all end stage kidney disease is due to diabetes. It is more common in Insulin Dependent Diabetes Mellitus (IDDM) than Non-insulin Dependent Diabetes Mellitus (NIDDM).
Kidneys act as a filtration system of the body and help to filter or excrete certain byproducts of carbohydrate and protein metabolism. Normally, albumin (protein) excretion through the kidneys is untraceable (<20 mg/minute or <30 mg/day). In Diabetes, damage to the kidney starts with gradual leakage of very small amount of protein (20-200 mg/minute) known as Microalbuminuria. At this stage kidney damage is preventable and even reversible. Later on larger quantities of protein may be lost in urine (called overt proteinuria). This condition, if untreated, may eventually lead to kidney failure.
It is important to note that High blood pressure may also cause rapid deterioration in kidney functioning. Therefore, it is imperative to maintain blood pressure at less than 130/80 mm Hg in people with Diabetes.
Kidney function can be assessed by Renal function test (mainly serum creatinine, blood urea, blood urea nitrogen, serum electrolytes i.e. Na+, K+, Cl- etc., total serum proteins and serum albumin)
Restricted protein intake (about 40 gm/day), along with tight blood glucose control, blood pressure control and regular monitoring of urine albumin levels are cornerstones in management of Diabetes associated kidney disease.
V. Pain in calf muscles : Affliction of blood vessels supplying the calf muscles manifests as pain in the calf while walking (claudication). In fact, this is an important manifestation of Peripheral Vascular Disease .
VI. Gum problems : Frequent gum infections are quite common in people with Diabetes because high blood sugar levels acts as a good medium for the growth of bacteria in the mouth. Dry mouth caused by certain medication may further aggravate dental problems. Gum problems may manifest as red, swollen, bleeding and painful gums, bad breath, dental cavities, loosening of teeth.
VII. Infections : Diabetes causes easy susceptibility to infections and delayed healing. The areas behind the scalp, genital area, urinary tract and feet are the commonly affected sites.
VIII. Foot Ulcers or Sores : The foot is the most vulnerable part of the body as far as compromised blood flow and recurrent and non-healing wounds are concerned. The blood of a diabetic usually has a higher than normal level of fats (hyperlipidemia) that tend to stick to arterial walls and clog it. This compromises blood flow to the foot.
The foot is also very prone to infections. Any infection of the foot is almost always due to multiple bacteria that are resistant to many common antibiotics. Therefore, even a trivial injury to the foot warrants proper medical care.
IX. Impotence : Impotence is the failure to maintain consistent erection with sufficient rigidity for sexual intercourse.
- Impotence in men with Diabetes can be due to associated complications of Diabetes, such as nerve disease. When nerves are damaged, small blood vessels don’t relax. This stops the blood vessels from growing larger with the flow of blood that makes the penis erect.
- High blood glucose levels may cause nerve damage which may result in loss of sensation and loss of the ability to get and maintain an erection.
- Some medications (e.g. beta-blockers, methyldopa, and diuretics) may affect sexual desire. In such a case, it is important to convey this to your doctor.
- Drinking too much alcohol can also cause impotence. It provokes the desire but takes away the performance.
- Smoking can cause impotence. Smoking makes blood vessel damage worse. It also slows down blood flow.
What causes complications in diabetes ?
Diabetes complications can be attributed to multiple factors.
A major cause of diabetes complications is excessive sorbitol formation. An enzyme called aldol reductase converts glucose to sorbitol, which in high levels is a tissue toxin. In diabetes, since there is excess glucose in the blood, sorbitol formation is in excess too, accounting for damage to eyes, nerves and kidneys.
Diabetes causes disordered metabolisms (chemical reactions taking place in the body) in the body. This affects thousands of tiny blood vessels, causing them to become narrow, which in turn restricts blood flow and causes leakage of blood contents into tissues (micro-angiopathy or tiny vessel disease). This is what causes eye damage (diabetic retinopathy), kidney damage (diabetic kidney), gangrene or ulcers of foot (peripheral vascular disease) and similar damages in the heart (diabetic cardiomyopathy) and brain.
When the cells become hungry (due to decreased blood flow), the fat stores release more fatty acids into circulation. The body behaves like a badly tuned car spewing thick smoke from the exhaust. In the body, the smoke appears in the form of high levels of Oxygen Free Radicals (charged particles with unbalanced electrons that can combine with vital chemicals to burn them). These radicals combine with fatty acids to make them oxidized (rancid). The oxidized fatty acids are sticky, and adhere to arterial walls. The circulating white blood cells (macrophages) try to engulf them and digest them, but fail. So they become loaded with undigested oxidized fatty acids (Foam Cells), which then become the trigger fatty deposits on the arterial walls. While the gradual clogging of arterial walls is called Atherosclerosis, the resultant damage is known as macro-angiopathy or large vessel damage. It is responsible for high blood pressure, heart attack and stroke.
Diabetes Control and Complications Trial (DCCT)
The largest and the most comprehensive diabetes study ever conducted showed that keeping blood glucose levels as close to normal as possible slows down the onset and progression of eye, kidney and nerve diseases caused by diabetes by upto 60%. The study findings are as follows :
Good control on blood glucose levels reduces :
- Risk of Eye diseases by 76%
- Nerve Diseases by 60%
- Kidney Disease by 50%
The study has also shown that a person with a history of poor blood glucose control can reduce the risk of diabetes complications, if he can maintain normal blood glucose levels