When blood sugar is falling, the stopper built into the body is the release of glucagon from the liver. However, when hypoglycemia is due to injected insulin - the stopper isn't entirely in place. Scientists explain how epinephrine (adrenaline) plays a major role in regulating glucose in times of low blood sugar and how this response could be adversely affected by the use of beta-blockers.
During insulin-induced hypoglycemia in dogs, the roles of epinephrine and glucagon were evaluated. The dogs fasted overnight to remove excess glucose from the blood. The dogs also had their adrenal glands removed. The adrenal glands are the source of epinephrine. Epinephrine is released into the bloodstream in response to physical or mental stress,to initiate the stimulation of glucose, among many other functions. Epinephrine and insulin were released at two different rates: a basal rate or a variable rate to simulate epinephrine response. When the blood sugar fell to 42 mg/dL, the dogs in the basal rate group failed to release glucagon, but the simulated epinephrine response group increased normally. The liver response to releasing glucose fell in the basal group but increased in the normal epinephrine response group. The researchers conclude that epinephrine must be responsible for this critical response to insulin-induced hypoglycemia.
Beta blockers are a common class of prescription drugs that counteract the stimulatory effects of epinephrine (adrenaline). Diabetics who inject insulin and take beta-blockers should be extra cautious of hypoglycemia. Hypoglycemic unawareness is already established for diabetics injecting rDNA insulin (genetically modified human insulin). Given the side effects of beta blockers, there is greater reason to be more aware of hypoglycemis unawareness -- yes, oxymoron. Those individuals who are on the brink of diabetes should avoid beta-blockers at all costs according to a study in The Lancet (January 2007) beta-blockers used for hypertension increase a patient's risk of developing diabetes.