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.
High blood sugar is one of the most important risk factors worldwide for a shorter healthy life expectancy. This emerges from a very large analysis of health data from 204 countries that compared 88 risk factors side by side. High blood glucose is identified there as one of the factors contributing most to disease and lost healthy life years.
How many years a stable blood sugar concretely yields cannot be stated precisely on the basis of this research. The analysis concerns population-level patterns and shows a clear association, but does not prove a direct cause-and-effect relationship. It is an association: people with higher blood sugar levels live on average fewer healthy years, but other factors also play a role.
What this means in practice: you do not need to have diabetes to benefit from stable blood sugar. The data cover the population as a whole, including people with mildly elevated values. Exercise, less sugar-rich food and sufficient sleep are the most well-supported ways to keep your blood sugar within a healthy range, although those interventions fall outside the claims examined here.
The available data for this answer say nothing about specific interventions, supplements or measurement methods for stabilising blood sugar. What you can do about this in practice is best discussed with your general practitioner, especially if diabetes runs in your family.
One large population study (GBD 2023, 204 countries, 88 risk factors). Associational; no RCT or mechanistic data available in the supplied claims.