Early development of type 2 diabetes leads to worse outcomes
More and more young people are being diagnosed with type 2 diabetes.
And it turns out that when you develop the disease early, your outcomes are worse — mainly due to an elevated risk of cardiovascular disease.
Professor Jonathan Shaw
Head, Clinical Diabetes and Epidemiology Lab, Baker Heart and Diabetes Institute
Dr Norman Swan
Norman Swan: Type 2 diabetes is the form of diabetes you develop as an adult and is caused by a combination of genetic and lifestyle factors, including obesity. It used to be called adult onset diabetes, but the disturbing reality is that you can now find adolescents developing the condition. You'd think it was the bleeding obvious that the longer you have diabetes, the worse it is for you, but that, believe it or not, has not been pinned down by evidence. But a huge study, over 700,000 Australians, has come up with some answers. One of the researchers was Professor Jonathan Shaw who heads the Clinical Diabetes and Epidemiology Lab at the Baker Heart and Diabetes Institute, and Jonathan's in our Melbourne studio. Welcome to the Health Report, Jonathan.
Jonathan Shaw: Good to be with you.
Norman Swan: So it isn't it's the bleeding obvious? Why would you do this study? Surely you kind of know this stuff?
Jonathan Shaw: Things that you think you surely know don't always turn out to be the case. One of the things that has really been driving this has been the observation of, as you were referring to before, about these youth onset, adolescents, and sometimes even children with type 2 diabetes, and it does seem from looking at some of those populations that their outcomes are very much worse than we see in adult onset diabetes. But the numbers of those people tend to be rather small, and it's hard to do really definitive studies with small numbers of people. So what we did was we looked across really essentially the adult range and found exactly the same thing, that the younger you get your type 2 diabetes, the worse the outcomes are.
Norman Swan: So you did this in 750,000 people who belong to the National Diabetes Services scheme, that's where they get their needles and their test strips from the government, free from the government. So they are registered there and you can follow them. And to what extent, how long and to what effect?
Jonathan Shaw: So what we see is for…we modelled it for every five years or for every 10 years of earlier onset of the disease, there's a measurable…so for every 10 years we saw 40% increase in the risk of dying from cardiovascular disease at the same age. So a 55-year-old, for example, who has had diabetes for 15 years has a 40% higher risk in that year, a 40% higher risk of dying from cardiovascular disease than someone who would develop diabetes 10 years later but is still of the same age. And so these are really important observations because it also gives us information about the benefit of doing things, even if all that you achieve is to delay the onset of diabetes. People tend to think of, you know, you are either going to get it or you are not going to get it, can you do something to prevent diabetes ever occurring. Often we find that that's difficult, but this seems to indicate benefit even just for delaying the onset. So somebody who was at high risk of developing diabetes in their 30s or early 40s, it turns out it makes a difference if they can delay it by even five years.
Norman Swan: And presumably it affects what's called the risk tools, you know, there are risk tools where you can work out what your risk is of getting a heart attack or stroke in the next five or 10 years. And that really asks a binary question; do you have diabetes or don't you? Does this mean that the other question is going to have to be asked in these algorithms is how long have you had diabetes…if yes, how long, and factoring that in to your risk?
Jonathan Shaw: Yes, so there are some algorithms mainly used among people with diabetes that do factor that in, you're absolutely right. But there is another component to this which is that when we as doctors look after people in their 30s and 40s and we do these risk questionnaires for cardiovascular disease, they give us an answer in relation to what's going to happen in the next five or 10 years. Even somebody who was at high risk at the age of 30 or 35 is unlikely to suffer a heart attack or stroke in the next five or 10 years, but they may be at very high risk of premature event which might occur in their late 50s or early 60s, and at this stage we don't have the tools really to calculate that kind of thing, that's another thing that we want to do with some of this information, is to try and translate that into tools to measure the risk of premature events and premature mortality.
Norman Swan: So one implication is if you can delay type 2 diabetes, and the Baker Institute has found that strength training, for example, can delay type II diabetes, and lifestyle change, then that's a good thing. And the other thing presumably is to control your other coronary risk factors, get your blood pressure, your cholesterol down as low as it possibly can get, and certainly don't smoke.
Jonathan Shaw: Absolutely. And the other interesting part of this is that, again, as doctors, as we treat people in their 30s and 40s who have established type 2 diabetes, we are probably not as aggressive as we should be with those other cardiovascular risk factors, the blood pressure and the cholesterol, because we perceive that those events are far away and that younger people really don't want to have multiple medications. But one of the other messages of this is that we probably do need to treat more aggressively people with young onset type 2 diabetes.
Norman Swan: Counterintuitively, you showed a reduced risk of dying from cancer.
Jonathan Shaw: Yes, so we have to be a little bit careful about that. So what we showed was…
Norman Swan: Well, you'd better be, I've been telling the world on the Health Report for years now that it increases your risk of cancer.
Jonathan Shaw: Yes, so you are 100% right about that. What we did show…
Norman Swan: Thank God for that.
Jonathan Shaw: What the data does show is that whilst for all groups of people with diabetes the risk of cancer is increased, somewhat curiously it appears that getting diabetes younger leads to a lesser increase than getting diabetes when you're older. It's a little bit uncertain as to how to interpret that…
Norman Swan: So does that mean you get a shock and you change your behaviour?
Jonathan Shaw: So that could be part of it, and it also could be…the other aspect of it could be that when you have a condition such as diabetes you tend to get a whole set of blood tests, you get things done regularly, you are under the more careful review of doctors, and therefore cancers may be picked up rather earlier. And so in that sense there may be some apparent benefits of an earlier diagnosis. But the real test of this is not individual disease mortality but is total mortality, and we definitely saw the adverse effect of younger onset on total mortality. So there may have been a slight gain for cancer in relative terms, but the loss for heart attack and stroke, and in fact for death from neither cancer nor cardiovascular disease was also increased. So overall it's definitely a bad thing to get diabetes when you're young, it means that anything that people can do to just put it off by a few years is beneficial, and that more aggressive treatment among younger people with type 2 diabetes is probably beneficial.
Norman Swan: Got the message. Thank you Jonathan.
Jonathan Shaw: Thank you.
Norman Swan: Professor Jonathan Shaw, who heads the Clinical Diabetes and Epidemiology Lab at the Baker Heart and Diabetes Institute in Melbourne.