Batman has Robin. The Lone Ranger has Tonto. And insulin has its own tough little partner: a hormone called amylin.
What’s that? You thought insulin worked alone, like Superman or Spiderman? Think again. Those guys only had madmen and criminals to fight. Insulin has the onerous task of keeping blood glucose in check while fending off challenges from food, stress, illness, and a slew of other hormones. However, like most sidekicks, amylin cannot replace or outperform insulin. Instead, it supplements insulin’s actions and allows insulin to do its job more effectively. This is particularly true after meals, when insulin by itself is no match for the blood glucose onslaught brought on by carbohydrates (sugars and starches) in the meal.
How it works
As most people with diabetes already know, insulin helps transfer glucose out of the bloodstream and into the body’s cells. It is produced by a group of cells in the pancreas called beta cells. But beta cells secrete more than just insulin; they also secrete amylin. People with Type 1 diabetes, whose beta cells have been destroyed by the body’s immune system, secrete no amylin at all. And people with Type 2 diabetes who have progressed to the point of needing insulin injections (or infusions from a pump) have limited beta cell capacity and thus produce insufficient amylin.
So why all the fuss about amylin? Those of us with diabetes have survived for years without it. But the goal, of course, is more than just survival. It is to manage blood glucose levels effectively so that we feel good, can perform our daily routines, and live long, healthy, productive lives. The natural hormone amylin, as well as its synthetic equivalent, pramlintide (available since 2005 under the brand name Symlin), helps improve blood glucose control after meals. It does this by prompting the following actions:
- Slowing digestion. Amylin slows gastric emptying, or movement of food from the stomach into the intestines. When carbohydrates stay in the stomach longer, they are converted to glucose and enter the bloodstream in a slower, more gradual manner.
- Blocking glucagon secretion. Glucagon is a pancreatic hormone that raises the blood glucose level by stimulating the liver to release stored glucose. It is usually secreted in response to stress or hypoglycemia (low blood glucose). Without amylin, most people with diabetes produce extra glucagon when they eat; this can contribute to after-meal blood glucose spikes. When taken with meals, Symlin suppresses the inappropriate release of glucagon by the pancreas.
- Enhancing satiety (the feeling of fullness). By helping to limit appetite and thus reduce the amount of food eaten during (and between) meals, amylin limits the potential for huge blood glucose spikes after eating.
So put it together: Symlin reduces mealtime glucagon secretion, slows digestion, and leads to decreased food consumption. This makes mealtime (rapid-acting) insulin’s job infinitely easier since there’s no dramatic blood glucose “spike” to deal with after eating. Instead, the blood glucose level tends to hold steady or rise only slightly after meals. Consequently, mealtime insulin requirements tend to decrease with Symlin use by an average of 10% to 20%, although this can vary considerably from person to person.
Overall, research shows that regular use of Symlin lowers the HbA1c level (a measure of long-term blood glucose control), the fasting blood glucose level, and blood triglyceride and cholesterol levels, and increases the percentage of time spent within one’s target blood glucose range. It also reduces blood glucose variability, or fluctuations in blood glucose level, which may be associated with long-term diabetes complications.