Hypoglycemia
From Diabetes Wiki
Hypoglycemia is a medical emergency produced by a lower than normal amount of glucose in the blood. The term "hypoglycemia" literally means "under-sweet blood".
Hypoglycemia is a fact of life for people with type 1 diabetes. Patients attempting to improve or maintain glycemic control suffer untold numbers of episodes of asymptomatic hypoglycemia; plasma glucose levels may be less than 50-60 mg/dl (2.8-3.3 mmol/l) 10% of the time. Severe hypoglycemia is constituted as a blood glucose of <50mg/DL. Hypoglycemia is the most common complication of Type 1 diabetes, and it is also the most dangerous. They suffer an average of 2 episodes of symptomatic hypoglycemia per week -- thousands of such episodes over a lifetime of diabetes and an episode of severe, at least temporarily disabling, hypoglycemia approximately once a year. An estimated 2-4% of deaths of people with type 1 diabetes have been attributed to hypoglycemia. While it is difficult to assess the absolute rates, the frequency of iatrogenic hypoglycemia is substantially lower in type 2 than in type 1 diabetes.
Hypoglycemia can produce a variety of symptoms and effects, but the principal problems arise from an inadequate supply of glucose as fuel to the brain, resulting in impairment of function (neuroglycopenia). Effects can range from vaguely "feeling bad" to coma and (rarely) permanent brain damage or death.
For patients with diabetes, hypoglycemia often occurs when a treatment to lower the elevated blood glucose of diabetes "overshoots" and causes the glucose to fall to a below-normal level.
From a strictly scientific standpoint, however, this is an oversimplification of what actually occurs in the body. Iatogenic hypoglycemia is typically the result of the interplay of absolute or relative insulin excess and compromised glucose counterregulation in type 1 and advanced type 2 diabetes. Decrements in insulin, increments in glucagon, and, absent the latter, increments in epinephrine stand high in the hierarchy of redundant glucose counterregulatory factors that normally prevent or rapidly correct hypoglycemia. In insulin-deficient diabetes (exogenous) insulin levels do not decrease as glucose levels fall, and the combination of deficient glucagon and epinephrine responses causes defective glucose counterregulation.
Furthermore, reduced sympathoadrenal responses can cause hypoglycemia unawareness. The concept of hypoglycemia-associated autonomic failure (HAAF) in diabetes posits that recent incidents of hypoglycemia causes both defective glucose counterregulation and hypoglycemia unawareness. By shifting glycemic thresholds for the sympathoadrenal (including epinephrine) and the resulting neurogenic responses to lower plasma glucose concentrations, antecedent hypoglycemia leads to a vicious cycle of recurrent hypoglycemia and further impairment of glucose counterregulation. In many cases (but not all), short-term avoidance of hypoglycemia reverses hypoglycemia unawareness in most affected patients.
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[edit] Symptoms
The symptoms of hypoglycemia may include shakiness, dizziness, sweating, hunger, difficulty paying attention, confusion, headache, going pale, tingling sensation in the mouth, and seizure. However, while the clinical presentation is often characteristic, the neurogenic and neuroglycopenic symptoms of hypoglycemia are nonspecific and relatively insensitive; therefore, many episodes are not recognized. Seizures can accompany hypoglycemia and is especially detrimental in children as it may adversely affect cognitive function in children.
[edit] Treatment
[edit] Oral intake of glucose
The blood glucose can be raised to normal within minutes with 15-20 grams of carbohydrates, which can be taken as food or drink if the person is conscious and able to swallow.
The quickest way to take this amount of glucose is by swallowing three glucose tablets, half a cup of fruit juice, or 5-6 pieces of hard candy. It is recommended that a diabetic person should keep a source of glucose close at hand to combat hypoglycemia. [1]
Starch is quickly digested into glucose, but adding fat or protein retards digestion. Symptoms should begin to improve within 5 minutes, though full recovery may take 10-20 minutes. Overeating does not speed recovery and will simply produce hyperglycemia afterwards.
[edit] Intravenous glucose
If a person is suffering such severe effects of hypoglycemia that they cannot be given anything by mouth, glucose can be given by intravenous infusion. Glucose is available for intravenous infusion in various concentrations; the highest is 50% dextrose.
[edit] Glucagon rescue
Glucagon is a hormone that rapidly counters the metabolic effects of insulin in the liver, causing glycogenolysis and release of glucose into the blood. It comes in a glucagon emergency rescue kit which includes tiny vials containing 1 mg, which is a standard adult dose. Side effects of glucagon can include nausea and headache, but these can also occur after severe hypoglycemia even when glucagon is not used. Risks of glucagon use are far lower than risks of severe hypoglycemia, and it can usually produce a faster recovery than calling for paramedics and waiting for them to start an intravenous line to give dextrose.
[edit] Research
Hypoglycemic episodes are serious and frightening, because they can produce cognitive effects that many patients worry will impair their brain function in the long term. However, a study published in "The New England Journal of Medicine" in May 2007 found that tight blood glucose control does not lead to long-term cognitive problems. [2]
The study's principal investigator, Alan M. Jacobson, M.D., head of Joslin's Behavioral and Mental Health Research Section and Professor of Psychiatry at Harvard Medical School, says, "[This study] provides further support for the safety of intensive diabetes therapy and the benefits of maintaining good glycemic control. While acute episodes of hypoglycemia can impair thinking and can even be life-threatening, type 1 diabetes patients do not have to worry that such episodes will impair their long-term abilities to perceive, reason and remember." [3]
The study, which was a follow-up to the Diabetes Complications and Control Trial (DCCT), is generally regarded as a well-funded and well-designed study, but there are some legitimate criticisms, especially regarding the marginalization of adverse effects (notably hypoglycemia).
For example, 40% of the cohort of more than 1,000 patients reported having had at least 1 incident of hypoglycemic coma or seizure. That is noteworthy, yet somehow never made it into the press release.
In addition, the DCCT is generally believed to have tracked 1,441 randomly selected diabetic participants for a period of 10 years. But the truth is that the DCCT began in 1983 with only 278 participants and the first 2 years were devoted to planning and feasibility studies. Of the original 278 participants in the DCCT, 8 dropped out (3%) and 11 died (4%) caused in large part by severe hypoglycemia. Changes were subsequently made to the eligibility criteria for the full-scale trial to exclude anyone with this very common short-term issue with insulin replacement therapy, which raises questions about exactly how random the DCCT was. Further, it suggests that in spite of a statistically significant increase in the incidence of hypoglycemia that was published in the DCCT trial results, the incidence of severe hypoglycemia most likely is underestimated as an "adverse effect" because of the exclusion previously noted. Now that intensive treatment is the standard treatment for virtually everyone with diabetes, the incidence of severe hypoglycemia-related hospitalizations stands at near record levels.
According to a study published in the October 18, 2006 issue of the Journal of the American Medical Association (JAMA), an estimated 56,000 "adverse effects" requiring patient emergency room treatment (most due to hypoglycemia) are reported each year, making insulin the medicine with the highest level of adverse effects.
[edit] References
Hypoglycemia in Diabetes; Philip E. Cryer, MD, Stephen N. Davis, MD and Harry Shamoon, MD; Diabetes Care 26:1902-1912, 2003. http://care.diabetesjournals.org/cgi/content/full/26/6/1902
Negotiating the Barrier of Hypoglycemia in Diabetes; Philip E. Cryer, MD and Belinda P. Childs, ARNP, MN, CDE; Diabetes Spectrum 15:20-27, 2002. http://spectrum.diabetesjournals.org/cgi/content/full/15/1/20
National Surveillance of Emergency Department Visits for Outpatient Adverse Drug Events; Budnitz et al.; JAMA.2006; 296: 1858-1866.
http://jama.ama-assn.org/cgi/content/abstract/296/15/1858
The effect of hypoglycemic seizures in children with diabetes. European Journal of Pediatrics; 1999, Vol. 158 Issue 10, pA865, 1p
Characteristics of severe hypoglycemia in the patient with insulin-dependent diabetes. Southern Medical Journal [South Med J] 1994 Jun; Vol. 87 (6), pp. 616.
- ↑ "Hypoglycemia", American Diabetes Association.
- ↑ Jacobson, Alan M.; G. Musen (May 3 2007). "Long-Term Effect of Diabetes and Its Treatment on Cognitive Function". The New England Journal of Medicine 356 (18): 1842-1852.
- ↑ "Tight Diabetes Control Does Not Impact Cognitive Ability In Type 1 Diabetes, Study Shows", Medical News Today. May 9, 2007.
