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HYPOGLYCEMIA: DRIVING UNDER THE INFLUENCE

GENERALLY

Used with the express permission of the authors at Medical and Toxicological Information (MTI)

Hypoglycemia (abnormally low levels of blood glucose / blood sugar) is frequently seen in connection with driving error on this nation’s roads and highways, including accidents with personal and material damage. Even more frequent are unjustified DUI or DWI arrests, stemming from hypoglycemic symptoms that can closely mimic those of a drunk driver. In this newsletter article we will examine the medical condition of hypoglycemia, its causes, including roles played by disease, alcohol and drugs, and give examples of actual cases in which hypoglycemia proved to be a decisive factor.

In a recent article on the diagnosis of hypoglycemia in car drivers, Kernbach-Wighton report on seven incidents, all involving hypoglycemic car drivers and the symptomatology observed after the incident. The brief case summaries in the adjoining table describe drivers who were involved in an accident and charged with driving while intoxicated or stopped for reckless driving. All of the examples are cases of drivers experiencing various degrees of hypoglycemia. Some are from the Kernbach report and several are from actual MTI cases. Just a quick run down of the cases will show quite clearly how easily the symptoms of hypoglycemia can be confused with the symptoms of intoxication.

In an individual with normal metabolism, blood glucose levels are regulated precisely and kept within a narrow range. This range can vary by individual and in most cases, by laboratory definition, hypoglycemia is defined as a blood sugar level below 60 mg/dl. However, most of the diabetes associations suggest that, in general, action should be taken to restore blood sugar levels to a normative range when the reading falls below 70 mg/dl. Diabetes patients and individuals who have certain kinds of tumors or possess other errors of metabolism, however, are unable to precisely regulate their glucose levels, which can range from extremely high or plunge to dangerous lows. The body, through the process of metabolism, breaks down the natural sugars (carbohydrates) that are eaten and converts them to glucose, which can then be absorbed from the intestines into the blood. At any given time during the day blood glucose reflects a balance of the amount of glucose absorbed from the intestine, the glucose converted and released by the liver into the blood and that going from the blood directly into the cells of the body. Only glucose can be utilized by the cells of the body and glucose needs insulin, which is produced by the pancreas, to get into the cells. Although insulin is the only hormone that directly helps the uptake of blood glucose into the cells, there are several key hormones that work in the opposite fashion--glucagon, epinephrine (also known as adrenaline), cortisol, and growth hormone.

+ Glucagon--stimulates glycogenolysis and gluconeogenesis (new glucose formation) in the liver and works to raise glucose levels and, like insulin, is manufactured in the pancreas. Works quickly.

+ Epinephrine (adrenaline)--stimulates glycogenolysis and glucoconeogenesis and is manufactured by the adrenal glands. Works quickly.

+ Cortisol--stimulates gluconeogenesis and causes the cells to respond less efficiently to insulin and is manufactured in the adrenal glands. Works slowly.

+ Growth Hormone--works to raise blood glucose levels by causing the cells to respond less efficiently to insulin and is released by the pituitary gland. Works slowly.

- Insulin--lowers blood glucose levels by allowing glucose to move into the cells and is manufactured in the pancreas.

The table below illustrates how glucose enters the blood and is taken up by the cells of the body:

Glucose can enter the blood from the intestines after food is digested and from the liver either by breakdown of stored glycogen (glucogenolysis) or by the formation from other substances (glucogenesis).

Glucose release from the liver is increased when glucagon, epinephrine, and cortisol levels in the blood are elevated and is decreased when insulin levels in the blood are high. Glucose exits out of the blood into the various tissues of the body, a process made possible by insulin and partially blocked by cortisol, epinephrine, and growth hormone.

When the cells of the body are deprived of nourishment via glucose, a condition called low blood sugar (hypoglycemia) can develop. Symptoms are usually divided into those affecting the body and those affecting the brain or central nervous system (CNS). Bodily symptoms may include rapid heartbeat, sweating, tremors, anxiety, hunger, and nausea. Those affecting the CNS are light-headedness, confusion, headache, loss of consciousness, seizures, delayed reflexes, and slurred speech. These symptoms are directly related to the brain or body not receiving enough glucose for use as an energy source. Often people who have frequent hypoglycemic episodes are unaware of how serious their symptoms are and may just feel a bit different when, in reality, they may be in a potentially dangerous state of confusion while engaged in activities such as driving which require a high degree of concentration. It is also possible for blood sugar to plunge quite suddenly, causing the individual to lose consciousness completely. This is such a serious problem for those with endocrine problems that numerous studies of hypoglycemia’s impact on driving ability and other activities that require a high degree of concentration have been carried out and reported on extensively in the medical literature.

CAUSES OF HYPOGLYCEMIA

DISEASE--Diabetics are unable to produce enough insulin and must supplement their bodily needs with daily injections or medication. This makes them particularly susceptible to adverse effects of hypoglycemia. The most common prerequisite for hypoglycemia is an overdose of insulin with too little carbohydrate intake or by taking other medications that decrease the blood glucose levels. Although not as common, other errors of metabolism, including insulin-producing tumors or non-islet cell tumors, can also cause hypoglycemia and account for driving errors that call attention to themselves, including, but not limited to, moving in wavy lines, driving in the opposite direction, or running off the road, and subsequently can lead to a driver being charged with a DUI when there may be a negligible amount of alcohol actually involved. Other disease states have also been implicated in hypoglycemia, including, but not limited to, cardiac problems, renal failure, and diseases of the liver.

ALCOHOL--Alcohol (ethanol) can lead to hypoglycemia when the liver is depleted of glycogen and will typically develop 6-24 hours after a moderate to heavy intake of ethanol in a person that has had an insufficient intake of food for 1 or 2 days. This can have a compounding effect and make the individual appear intoxicated when in fact the person’s actual blood alcohol concentration (BAC) may be well below the legal limit. Ethanol can also potentiate the hypoglycemic action of certain classes of drugs like sulfonylurea and insulin.

DRUGS--Insulin and sulfonylureas diabetes medications that stimulate insulin release are the two leading causes of drug-related hypoglycemia; however, many prescription drugs, including some over-the-counter (OTC) medications can directly or indirectly cause hypoglycemia in an unsuspecting user. Examples include salicylates, including aspirin, when taken in large doses; sulfa medicines, used to treat infections; pentamidine, used to treat pneumonia; and quinine, for treating malaria. Pseudoephedrine is found in many over-the-counter cold medications and is one of several drugs that is a close structural analogue of the true amphetamines and has actions and side effects similar to the hormone epinephrine (adrenaline). This OTC can have the effect of speeding up the metabolism to use glucose more rapidly and thereby enhance a hypoglycemic condition. There are also a wide range of drug combinations that can lead to hypoglycemia or enhance an already existing condition.

OVEREXERTION-- Too much or prolonged exercise is another way the body can speed up metabolism and rapidly deplete stored glucose. Sometimes exercise can have a prolonged effect in lowering blood glucose levels--up to 24 hours. Fright or anxiety can also cause the body to overreact and, as with overexertion, can expedite the release of adrenaline speeding up the metabolism and lowering glucose levels.

DIET SODA--One of the most common sweeteners used in diet drinks is Aspartame, which contains the amino acid phenylanine, a chemical known to produce a higher insulin response. This response can be extremely pronounced in endocrine-compromised individuals. Studies in the medical literature have shown this response to be 101%--103% greater than with a similar beverage containing a carbohydrate sweetener. Drinking diet soda alone or in combination with ethanol could only serve to enhance a state of low blood sugar.

CONCLUSION

As we have briefly outlined in this issue of MTI Review hypoglycemia is a serious problem for many individuals with faulty metabolism. The ramifications of the condition can sometimes go far beyond the surface medical and scientific issues regarding the physical health of the patient. The problems range from maintaining blood sugar levels in order to live a “normal” life, to life-threatening risks due to sudden spikes or plummets of blood sugar levels, to being falsely accused of driving in an intoxicated condition during periods of an unstable metabolism, a charge which can have long-term consequences for a person’s life and career. And, if anything, the problem is only going to get worse. The National Health and Nutrition Examination Survey, released in September 2003 and published by the Center for Disease Control and Prevention in the September 5, 2003 edition of its Morbidity and Mortality Weekly Report, indicates that one in seven Americans have diabetes or blood sugar problems that are leading toward diabetes. In fact, world health officials meeting in August, 2003 in Paris at the International Diabetes Federation Conference proclaimed that the world is facing a “diabetes catastrophe” with more than 300 million people worldwide facing a serious risk of developing diabetes. With the numbers of people with blood sugar problems and other errors of metabolism rising, it is becoming more important than ever for individuals, medical professionals, and law enforcement personnel to recognize both the danger signals of hypoglycemia and to understand that although the condition mimics closely those who irresponsibly abuse alcohol, judicious use of sound science principles can ensure that a health compromised individual is not unjustly punished for a pre-existing physical condition.

Complete bibliography available upon request.

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