Insulin is an endocrine hormone produced by beta cells of the pancreas. Adequate production and release of insulin is necessary for proper metabolism of sugars in the body; glucose is the most common sugar in the body. The binding of insulin to its receptor on cell surfaces causes the movement of potassium into cells, thereby resulting in a decrease in blood potassium levels. Hypokalemia, or low blood potassium, is commonly associated with leg cramps.
Insulin and Hypokalemia
Since the release of insulin results in movement of potassium into the cell, the balance of potassium in the blood is partly dependent on insulin. In a healthy person, insulin rarely causes hypokalemia because normal functioning kidneys adjust excretion of potassium according to events in the body. When hypokalemia results from the release of large amounts of insulin into the blood, the kidneys slow the excretion of potassium. The link between insulin and potassium is more apparent in diabetics because their lack of insulin results in high blood glucose and potassium levels, which causes dysfunction of various organ systems; the administration of insulin results in the decline of potassium levels and restoration of normal glucose levels.
Potassium Regulation
The maintenance of normal blood potassium levels depend on adequate intake of dietary potassium and appropriate control of potassium excretion. The kidneys are chiefly involved with potassium excretion; they respond to aldosterone, a hormone produced by the adrenal glands. Aldosterone acts in the kidneys, thereby resulting in increased potassium excretion. Aldosterone is released when blood potassium levels are higher than normal; when blood potassium levels are lower than normal, the release of aldosterone is inhibited, which causes the kidneys to hold back potassium.
Leg Cramping
Leg cramping is the involuntary contraction of muscles in the legs, which prevents the muscles from relaxing; leg cramping is usually associated with forceful contractions that can fix the legs to a certain position. According to "Cracking the Metabolic Code," diabetes -- marked by low blood insulin levels -- is commonly associated with hypomagnesemia or low blood magnesium; leg cramping is a symptom of hypomagnesemia; also according to "Applied Physiology in Intensive Care Medicine," hypomagnesemia is commonly associated with hypokalemia, which is also a cause of leg cramping.
Preventing Leg Cramps
Leg cramps can occur during exercise, therefore it is advisable to stretch your muscles and warm-up for a couple minutes before engaging in active exercise. Adequate hydration with fluids is also important before exercise because prolonged physical activity is associated with loss of water and electrolytes, such as sodium and potassium. Diabetics must take recommended doses of insulin to prevent subsequent development of hypokalemia. Diseases involving the digestive system may result in abnormal loss of potassium from the body, such diseases must be adequately controlled to prevent hypokalemia. Conditions that cause hypomagnesemia must also be addressed early on to prevent leg cramping; diseases that result in hypomagnesemia include alcoholism, inadequate magnesium intake, pancreatitis and medications.
References
- Unbound Medicine: Hypokalemia
- "Cracking the Metabolic Code"; Magnesium; James B. LaValle; 2004
- "Applied Physiology in Intensive Care Medicine"; Magnesium in Critical Illness; Michael R. Pinsky, et al.; 2009
- "Harrison's Principles of Internal Medicine"; Dennis L. Kasper M.D., et al.; 2005
