Symlin Up Close
How people are benefiting from this injected drug
Shelley Almburg, 49, was first diagnosed with type 1 diabetes at the age of 16. She uses an insulin pump to maintain her blood glucose.
But Almburg was finding that her glucose still sometimes spiked after eating. And, over the years, she put on some extra weight. So she decided to look into Symlin. "I thought it would keep my blood sugars more even," she says, "and I really wanted to see how the weight-loss thing worked, too."
Symlin, or pramlintide, is an injectable synthetic version of the hormone amylin and is prescribed to people with either type 1 or type 2 diabetes who use mealtime insulin but who have not achieved adequate blood glucose control.
Symlin offers another benefit as well, the "weight-loss thing" Almburg alluded to: It makes some people feel fuller after eating. Consequently, they eat less and lose weight.
Not everyone who uses Symlin will lose weight. But for some, weight loss on the drug can be significant: 5 percent of body weight or more. Almburg's doctor added Symlin to her medication regimen in November 2006. At the time, she was carrying about 165 pounds on her 5'1" frame, placing her weight in the obese range. "Probably in 3 months, I lost 21 pounds," she says. "It worked really fast!"
Amylin, the hormone that Symlin replaces, is normally secreted along with insulin by the beta cells in the pancreas. Diabetes damages or destroys these cells, reducing or eliminating production of both insulin and amylin, which causes blood glucose levels to rise.
Symlin, which is injected at mealtimes either before or along with insulin (but never in the same syringe—it must be injected separately), slows digestion and in turn, delays the release of glucose into the bloodstream. The drug also suppresses secretion of glucagon, a pancreatic hormone that triggers the release of glucose from the liver. All of these actions result in lower and more stable blood glucose.
"I think a lot of people don't understand how important this hormone amylin is," says Steve Edelman, MD, a professor of medicine at the University of Califonia, San Diego, who has done research on Symlin. "It is difficult to control glucose in diabetic patients on insulin alone," Edelman says. "Symlin mimics the natural hormone amylin, and amylin and insulin are sister hormones—they work together."
Edelman, who has type 1 diabetes, uses Symlin himself. Although he has not lost weight on the drug, Edelman believes that the potential for weight loss is an important benefit of Symlin. While some studies show a 5 percent or greater drop in body weight on Symlin, a clinical trial involving 296 people with type 1 diabetes led by Edelman found that the average weight loss of those who added Symlin at mealtime was only 2.9 pounds over 29 weeks. However, the control group, who were using insulin and injecting a placebo medication, gained 2.6 pounds over the same time period.
Weight gain is common among patients on insulin, Edelman adds. "There are only two drugs that I know of for diabetics that cause weight loss: Symlin and Byetta." Also introduced two years ago by Amylin Pharmaceuticals, Byetta (pramlintide) is an injectable adjunct therapy for people with type 2 diabetes who take oral medications, such as metformin or sulfonylureas, but still need greater glucose control.
Symlin is also being tested as a weight-loss drug in nondiabetic patients. In a 6-week trial of Symlin reported in June 2007 in the American Journal of Physiology: Endocrinology and Metabolism, obese patients who injected Symlin three times daily before each meal lost an average of 4.5 pounds. The control group, which injected a placebo medication, maintained their weight.
Control Comes First
However, says Cathy Martin, a diabetes specialist at the University of Michigan, it's important not to over-emphasize Symlin's weight-loss potential. "The purpose of prescribing the drug is to help people achieve the best glucose control they can," she says. "We can tell people there is a chance they may lose weight, and that's a bonus, but it's not the reason for prescribing the drug."
Symlin can be tricky to use, Martin adds. When it was first introduced, some cases of hypoglycemia (low blood glucose) were reported. Dosing instructions now recommend that Symlin patients take half their mealtime insulin dose to avoid low blood glucose when starting out. Some patients also made the mistake of mixing insulin with Symlin and injecting the two drugs together. The Symlin injector pen, approved by the FDA in late September, should eliminate that bit of medication confusion.
As for side effects, nausea is the most common one reported, but most patients find it disappears over time. "It was a process for me, learning how to use Symlin along with the insulin," says Shelley Almburg. "I had some low blood sugars, and some nausea at first. But now, my blood sugar has stayed level, and my weight has stabilized at 21 pounds lower. So for me, it's worth the effort."
Amanda Spake is a freelance writer from Churchton, Md.