There's mounting evidence that you age more quickly if you have a high blood sugar level. The latest indication comes from Leiden University Medical Center in the Netherlands and will be published soon in Age. According to the article, the higher your glucose level, the older your face looks.
Doctors have been doing it for ages: they estimate the age of a new patient and then compare their guess with the patient's real age. If the guess is on the high side, then it's a sign that the patient's health is not optimal.
The researchers used this same technique. They gave a panel of 60 assessors photos of the faces 602 people in their fifties and sixties, and asked them to estimate how old they thought the people in the photos were.
We tend to assume that people with a low BMI are older than is the case. Everything that says money works the other way: expensive clothes or a chic hairdo make people look younger. When the researchers had corrected the estimates for these kinds of factors they got the figure shown below. As you can see, the non-diabetic 50-60 year-olds look older the higher their fasting glucose level is. And the diabetics look oldest of all.
The researchers suspect that a high glucose level causes more molecules like pentosidine [structural formula shown below] to occur in the body. Pentosidine is an advanced glycation end product, or AGE.
AGEs are formed when the body attaches sugars to amino acids. Most of the compounds have the tendency to attach themselves to amino acids in body tissues.
If this happens in the skin, structures build up in the collagen and elastin that get in the way of repair processes. And that's how AGEs accelerate the skin's ageing process. AGEs do the same in a lot of other places too, like the blood vessels, kidneys and the cartilage. So the ageing that's visible in the face is an indication of the invisible biological ageing.
The 'rejuvenating effect' of a lifestyle that leads to a lower glucose level is not very big, according to this study. But it's worth noting that the study probably underestimates the effects of a high blood sugar level. The photos that the researchers used were of participants in the Leiden Longevity Study; and these people have genes that predispose them to age slowly.
Age (Dordr). 2011 Nov 20. [Epub ahead of print].