Diabetes mellitus occurs when there is a deficiency (relative or absolute) of insulin, which normally helps keep blood glucose levels low. People with diabetes mellitus have raised blood sugar levels and are at greater risk of developing circulatory disease. This is because of an increased predisposition to atherosclerosis. Although relatively few studies have examined the importance of other risk factors in the development of CVD in diabetics,(62,63) recent evidence suggests that diabetic smokers have a greater than threefold incidence of CVD than diabetic non-smokers, and even ex-smokers with diabetes have an increased risk of developing CVD.(63)
Diabetics who smoke also appear to have increased risk for, and more rapid development of, albuminuria (the presence of albumin, a blood protein, in the urine).(64) Albuminuria is an indicator of small blood vessel disease in the kidneys. This small blood vessel disease is usually widespread and particularly affects the eyes, brain, heart and limbs.
Diabetes mellitus and cigarette smoking are the two major risk factors for PVD and subsequent amputation of lower limbs.(18) Development of PVD tends to be more rapid and occurs at younger ages in diabetic smokers than in diabetic non-smokers.(18)
Peptic ulcer disease refers to ulcer formation in the stomach and duodenum. Epidemiological studies have found that cigarette smoking is causally associated with peptic ulcer disease. It is estimated that 41% of peptic ulcer disease in males and 33% of the disease in females may be attributed to smoking.(4)
The risk of peptic ulcer disease is dependent on the amount smoked and the duration of smoking. Smokers with peptic ulcer disease have an increased risk of death from this disease compared with non-smokers with the disease. The risk is, on average, twice as high for smokers as for non-smokers, and appears to be greater for gastric than for duodenal ulcer disease. Smoking also retards the healing of peptic ulcers, and recurrence of ulcers is more likely to occur in smokers.(1) Nicotine appears to be the causal agent in ulcer development, through alterations to gastric acid secretions and impairment of the protective mucosal stomach lining.(56)
Although smoking is not, in itself, a cause of hypertension (high blood pressure), hypertensive smokers are at greater risk of developing malignant (or accelerated) hypertension,(56) in which the blood pressure increases rapidly to dangerous levels. Unless controlled, malignant hypertension leads to cerebral haemorrhage, stroke, heart attack, or renal failure.
Although blood pressure increases briefly following smoking a cigarette, in general, smokers have a slightly lower blood pressure than non-smokers.(13) This apparent inconsistency between short and long term effects of smoking may be due to development of tolerance by the smoker and lower body weight among smokers.(16)
Smokers generally weigh less than non-smokers of comparable age, and gain weight following cessation. Studies have shown that smokers tend to eat less sweet food than non-smokers, but to increase energy intake following quitting. Smokers also have an increased metabolic rate, meaning that their resting energy expenditure is greater than that of non-smokers.(2) No significant differences in physical activity between smokers and non-smokers which could account for these weight changes have been observed.(56)
Nicotine appears to be the agent in tobacco smoke responsible for these effects, both suppressing appetite and increasing metabolic rate.(56) See also Chapters 5 and 11 (for information on the properties of nicotine) and Chapter 12, Section 7 (for information on weight gain).
Many studies have shown that cigarette smoking exerts a deleterious effect on the inflammatory response to lung infection.(2) While there is a higher level of activation of the lung's immune defence mechanisms, this is not accompanied by an increase in the lung's ability to fight infection. There is evidence that the pulmonary immune system is less efficient in those who smoke, with smokers being more predisposed to severe influenza infection than non-smokers.(2)
While some research has linked smoking by individuals who are HIV (human immunodeficiency virus) seropositive with a more rapid development of AIDS (acquired immune deficiency syndrome),(65,66) other research has reported conflicting findings.(67,68,69)
Smoking is a major risk factor relating to surgery and the period immediately following surgery.(70) This is due to the effects of smoking on tissue oxygenation, heart rate, airways clearance, immune response, and circulation. Smokers, on average, also require higher doses of analgesia for pain relief.(70)
The Faculty of Anaesthetists of the Royal Australasian College of Surgeons advises that smokers be counselled to stop smoking completely, or failing that, to abstain for at least six to eight weeks before surgery. Abstinence for the 12 hours immediately prior to surgery is particularly important for maximum tissue oxygenation.(70)
The Faculty of Anaesthetists' statement on smoking and its effects on surgery is reproduced in full, with references, in Appendix II.
Adequate blood flow to the skin is an important factor in wound healing.(56) The effects of nicotine through smoking have been shown to delay wound healing and reduce the success rates of surgical flaps and skin grafts.(56,71)
Smoking is a risk factor for developing Crohn's Disease (chronic inflammation of the small intestine),(72,73) and may also be a factor in recurrence of the disease following surgery.(73) It is estimated that 36% of Crohn's Disease in men and 40% in women is caused by smoking.(4)
The National Injury Surveillance Unit (which monitors data from 50 participating Australian hospitals) has recorded 131 burns caused by a child walking into a lit cigarette, or being otherwise struck by a cigarette, over the period 1986-1991. Of these cases, 78 involved partial thickness burns to the eye. An additional 67 cases involved burn injuries from cigarette lighters and lighter fluid.(74) The Victorian Injury Surveillance System has reported that there were 32 cases of children ingesting cigarettes between 1988 and 1994. (75)
In Victoria between 1989 and 1992 the coroner investigated 31 smoking related and 8 match related deaths. Most of these deaths were due to burns and smoke inhalation.(75) In 1992, an estimated 31 people died in fires caused by cigarettes. It is estimated that 23% of fire injuries are caused by cigarette smoking.(4)
Smokers subject their bodies to continued exposure to low amounts of nicotine, leading to tolerance. However dizziness, nausea and vomiting may occur following smoking before tolerance is established.(56)
These symptoms also accompany cases of nicotine poisoning, which may occur through ingestion of tobacco or other products containing nicotine (such as pesticides), or through absorption of nicotine through the skin (again, through exposure to pesticides, or through exposure to raw tobacco leaves).(56)
Nicotine intoxication causes nausea, vomiting, abdominal pain, diarrhoea, headaches, sweating and pallor. In more extreme cases it can lead to dizziness, weakness and confusion, followed by convulsions, a drop in blood pressure, and coma. Death may occur through respiratory failure.(56) Although the nicotine contained in a single ingested cigarette butt is enough to kill an infant,(76) death due to ingested tobacco is extremely rare due to the vomit response and early metabolism of the nicotine.(56) (For further information on the properties of nicotine, refer to Chapters 5 and 11).
The National Injury Surveillance Unit has on record data from 114 cases involving ingestion of cigarettes by children between 1986 and 1991. Thirty-five percent of those who had eaten cigarettes were subsequently admitted to hospital.(74)
Smoking has been linked with the development of Graves' ophthalmopathy,(77,78,79) an autoimmune disease which affects the muscles behind the eyeball, causing the muscles to swell and the eyes to protrude. Increased incidence of the disease among smokers may be due to deleterious effects of smoking on the immune system.(80)
Smoking has also been linked with the development of cataracts,(81,82,83) and with an increase in the likelihood of requiring surgery for cataracts.(83) Smokers of twenty or more cigarettes a day increase their risk of developing cataracts by up to three times compared to the risk of never-smokers or former light smokers.(81,82) Former moderate to heavy smokers appear to carry some excess risk of developing lens opacity.(81)
The carbon monoxide (CO) contained in cigarette smoke is also considered to be a hazard to vision, particularly at altitude.(84) When inhaled, the bloodstream absorbs CO far more efficiently than it does oxygen. This causes a lower concentration of oxygen available to body organs and tissues, causing hypoxia (shortage of oxygen). Among other things, hypoxia leads to delayed response time and impaired night vision. The effects of hypoxia are accelerated at altitude. For example, the CO taken up by the blood from the equivalent of three cigarettes at sea level, leads to a 'physiological' equivalent of being at 12,000 feet. This has obvious implications for pilots of aircraft.(84) A Canadian study noting an increased incidence of motor vehicle crashes among smokers has also suggested that visual impairment caused by CO toxicity may be a contributing factor.(85) See also Chapter 5, Section 1 for further information about the effects of CO on the body.
Research has shown that cigarette smoking appears to have an adverse effect on sense of smell. Current smokers were almost twice as likely to have some deficit in their sense of smell compared to never-smokers. Impairment follows a dose-response relationship, with olfactory function gradually recovering after quitting smoking. The researchers suggest that the loss of sense of smell may occur through damage or alteration to the mucosal lining of the nasal passages by tobacco smoke, thereby altering odorant transport, by adaption or habituation of the mucus lining to the insult of tobacco smoke, or by nasal airway constriction.(86)
Smoking is among the risk factors for back pain(87,88,89) and appears to be independent of other factors, with smokers reporting 40% more back pain than non-smokers.(88) A dose-response relationship is evident between heavy smoking and severe pain.(89) The relationship between smoking and back pain may be due to impaired blood flow to the spinal region, making it more vulnerable to injury, jarring from constant smoking-caused coughing,(89) or diminished bone mineral content.(87)
Several studies have shown that skin quality is affected by exposure to tobacco smoke, independent of age and sun exposure. Smokers appear to experience earlier and more pronounced facial wrinkling, especially around the eyes and the mouth, related to the amount smoked and duration of exposure.(90,91,92,93)
Other facial features consistently noted are a grey appearance to the skin,(90,91) gauntness, a leathery, worn or rugged appearance, or orange, purple or red skin tones.(91)
Exposure to cigarette smoke could affect the skin in several ways. External exposure to irritant chemicals in smoke could promote chronic squinting, drying or skin irritation which could lead to wrinkles. Toxic components of smoke absorbed by the body may impair blood flow to the skin or cause connective tissue damage. Cigarette smoke has been shown to damage collagen and elastin in the lung, substances also important to skin maintenance.(93)
It has been noted that education campaigns which make mention of the facial effects of smoking may have more salience among the young, as the threat of developing other diseases may appear too distant to have a deterrent effect.(93,94,95)
Research has shown that smoking is an independent risk factor for snoring. The heavier and longer the duration of smoking, the more likely the smoker is to snore.This is probably due to upper airway inflammation, and cough and sputum production caused by smoking.(96)