I know this might be unrelated, so just a guess, but would people who are doing weekly injections, maybe bi-weekly or daily, also be more prone to take the flu shot and generally be medically more active, due to their inclination of trying to improve their weight/sugar levels using a medical injection. The article also mentions that this only proves correlation and not causation, which is hats off to gizmodo, but can be interesting if causation is proven in a future study