Ozempic added 92 days to the life of mice

On September 2, Nature published a study that went around social media in 48 hours.

Mice treated with semaglutide, the molecule behind Ozempic and Wegovy, lived longer than untreated mice.^[1]

It is the first signal of its kind for a molecule already sitting in pharmacies.

The protocol

Healthy female mice, 20 months old.

That is late. Roughly a human in their sixties.

Daily semaglutide injection, continued to the end of their lives.^[1]

The result

Median lifespan: 834 days against 742.

That is 92 days, or 12%.^[1]

The detail that makes the number solid: causes of death were the same in both groups.

Semaglutide did not remove one disease. It pushed death back on several fronts at once.

That is the signature of a general slowdown of ageing, not a targeted treatment.^[1]

The benefits

They did not just live longer. They aged better.^[1]

• More movement and more exploration. An old mouse hugs the walls; these went back to the middle.
• Better spatial memory.
• Better coordination, more strength, more endurance.
• Better glucose handling.
• Weight loss that came from fat: percentage lean mass went up, not down.

They also cut their own intake by 24%. Against mice held at the same calorie level, they match on strength and endurance, and do better on exploration, memory and glucose.^[1]

So the effect is not just eating less. And it comes without the permanent hunger of strict dieting.^[3]

This is not an isolated signal

The study lands after several years of results pointing the same way. All of them on a GLP-1 treatment.

• SELECT: 20% fewer major cardiovascular events, in people with overweight and no diabetes. Semaglutide 2.4 mg weekly, the Wegovy dose.^[4]
• FLOW: less kidney damage and lower mortality in type 2 diabetes. Semaglutide 1 mg weekly, the Ozempic dose.^[5]
• And trials under way on the liver and on Alzheimer's, again with semaglutide.^[1]

Every time, the benefit runs ahead of what weight loss alone would explain.

What we do not know yet

These are mice. Females only.^[1]

The mechanism behind the extra effect has not been identified.^[2]

And nothing is proven in humans on longevity. Trials are starting; it will take years.^[2]

What I take from it

"Ozempic makes you live longer" runs too fast. But the opposite would be just as wrong.

It is the first time a molecule already prescribed to millions reproduces, in a mammal, what only food deprivation could do.

I increasingly think we are looking at a class of molecules that goes far beyond weight loss. GLP-1, or whatever comes after it.