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Breaking News on Tirzepatide – the Most Buzzworthy Drug in Development

By Eliza Skoler, Ursula Biba, and Rhea Teng

Results released today by drug company Lilly show that the new combination therapy may be extremely effective for people with type 2 diabetes: it reduced A1C by an average of 2.5 percentage points and led to a weight loss of 24-28 pounds.

Early results from two clinical trials of Lilly’s tirzepatide were published this morning, showing that the new type 2 diabetes drug can lead to significant weight loss, A1C reduction, and less hypoglycemia among people with type 2 diabetes. Tirzepatide combines two types of drugs into a once-weekly medication. This new glucose-lowering combination therapy is called a “dual GIP and GLP-1 receptor agonist” and is currently in development to help people manage type 2 diabetes.

The trials, referred to as SURPASS-3 and SURPASS-5, included almost 2,000 participants with type 2 diabetes who took different doses of tirzepatide, insulin, or placebo medication for 40 and 52 weeks. Both trials investigated 5 mg, 10 mg, and 15 mg doses of tirzepatide and found that all doses led to impressive reductions in A1C and body weight.

Among participants taking 15 mg of tirzapetide:

  • A1C levels went down nearly 2.5 percentage points from a starting point above 8%.

  • Average weight loss was 25 pounds.

The change in A1C was particularly important. More than half of the participants taking any dose of tirzepatide across both trials achieved an A1C level below 5.7% – this is the level seen in individuals without diabetes. 

Here’s what the two clinical trials studied:

  • SURPASS-3 was a 52-week randomized, open-label trial, that compared the effects of tirzepatide to insulin degludec in adults with type 2 diabetes. At baseline, participants had an average A1C of 8.17%, and weighed 207 lbs.

  • SURPASS-5 was a 40-week, randomized, double-blind trial, that studied the effects of tirzepatide compared to a placebo in addition to insulin glargine (with or without metformin use) in adults with type 2 diabetes. At baseline, participants had an average A1C of 8.31%, weighed 209 lbs, and took 38 daily units of insulin.

Hypoglycemia (low blood sugar) can be a concerning side effect of new diabetes therapies. However, in SURPASS-3 the tirzepatide group experienced less than one hour a day of hypoglycemia; those on insulin degludec showed almost seven times more hypoglycemia each day. Additional side effects were primarily gastrointestinal; people taking tirzepatide did experience more nausea and diarrhea in both trials.

While these results are both exciting and promising, tirzepatide has not yet been approved for people with type 2 diabetes. We’ll be sure to keep you updated as more results are released.

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