What does insulin do to the ageing process?
Chronically too much insulin is probably bad for healthy ageing, but science does not yet know precisely what the ideal insulin balance is for you. Eating less processed food and moving more are the best-supported steps for keeping your insulin metabolism in good shape.
In animal research the link between insulin signalling and ageing is remarkably strong. In roundworms, lifespan doubles when the insulin receptor is less active. Similar effects have been found in fruit flies and mice. The pattern is consistent: less insulin signalling, longer life across multiple animal species.
In humans the picture is more complicated. A chronically elevated insulin level, often combined with insulin resistance, is associated with a higher risk of cardiovascular disease, dementia, high blood pressure and type 2 diabetes. These are associations found in observational research, not proof that insulin directly causes those diseases. At the same time, research shows that ageing itself impairs the pancreas, the breakdown of insulin and the sensitivity of tissues to insulin, which can set off a negative spiral.
High insulin levels also suppress the ability of cells to clear out damaged components. That clean-up mechanism, which keeps cells in good working order, functions less well under persistently high insulin concentrations. At the same time, poorly functioning proteins accumulate, the energy factories inside cells become less efficient and oxidative damage increases. All of these processes play a role in ageing.
Incidentally, the effect of insulin and growth-factor signalling is not simply 'more is worse'. Mouse studies show that strong growth-factor signalling actually benefits the hearts of young animals, but worsens heart function and shortens life at older ages. In humans, unlike in animals, low growth-factor activity is associated with a higher risk of cardiovascular disease and diabetes. High activity increases the risk of cancer. An optimal middle ground appears to exist, but what that looks like in humans precisely is still largely unknown.
Restricting food intake and exercising can lower insulin levels and insulin resistance and strengthen protective cellular processes. The direct evidence that this also slows ageing in humans is, however, limited and largely indirect.
All claims are based on reviews and observational research (PMID 9252323, 18948730, 19103250, 37854186, 33706949, 15539808, 35616058, 33917519). No randomised trials or meta-analyses are available in the sources. The animal data are causal; the human data are largely observational.
Does insulin resistance accelerate ageing?
Insulin resistance is associated with measurably faster biological ageing, greater muscle loss, and possibly a higher risk of cognitive decline. Regular physical exercise is the best-supported way to slow this down.
Does someone with diabetes age faster biologically?
Yes, diabetes noticeably accelerates biological ageing: the risk of cardiovascular disease, dementia, and premature death increases, and keeping blood sugar well under control is the most direct way to slow that process.
Do diabetes pills (SGLT2 inhibitors) also work against ageing?
For people with heart or kidney problems, large trials show that SGLT2 inhibitors clearly do more than lower blood sugar alone. As an anti-ageing pill for healthy individuals, it is still too early for a practical recommendation.
What does stable blood sugar do for healthy ageing?
A stable, low blood sugar is associated worldwide with more healthy life years. The association is clear, but the exact gain per individual cannot be quantified on the basis of this research.
Does excess weight accelerate ageing?
Excess weight demonstrably accelerates biological ageing, but metabolic health counts at least as heavily as the number on the scale. Losing weight and exercising help, and the earlier you start, the greater the benefit.
What is insulin resistance and can I reverse it?
Insulin resistance can in many cases be substantially reversed, and exercising more combined with a healthier diet are the best-evidenced approaches for doing so. Starting early pays off, because the longer the vicious cycle runs, the harder it becomes to break.