Getting Type 1 diabetes is seen by many people as a complete disaster. Effective treatment has been around for less than a hundred years and before that life expectancy after diagnosis was very short, with most patients dying before they had reproduced.
Although there are environmental triggers, the existence of diabetes is largely determined by a number of genes. How is it that these genes persist in a population over generations if many of the carriers of those genes do not reproduce?
We can infer an answer to this question by looking at single gene diseases in which the situation is clearer. For example thalassaemia, sickle cell disease, G6PD and other red cell disorders gave heterozygotes some resistance to the effects of malaria, the cystic fibrosis gene protected against cholera and the gene for haemochromatosis was useful in dealing with anaemia due to hookworm and other causes.
So these serious diseases persist because their effects were not all bad.
(Aside: I am aware of research showing how a gene with effects that are all deleterious at a young age can persist in a population, but I think this mechanism does not apply to diabetes. Genetic diseases that kill the elderly do not impede the survival of the gene. In fact they may enhance it)
Why do Type 1 diabetic genes persist in the population. The answer has to be that some of these genes confer a survival advantage. What advantage? I don’t know but there must be one. It may be that diabetic genes improve performance to a small degree in a broad range of activities and a specific advantage will never be determined. ( the evidence in favour of this will be in a later post)
I used to think about what life would be like if I didn’t have diabetes. I wouldn’t have the hassle, but on the other hand I wouldn’t have the advantages. Maybe my skiing abilities would be much worse.
So don’t hate your diabetes. Learn to deal with the downsides, so that the good effects can shine through.