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Advances in medical care have led to type 1 diabetes boom

Discussion in 'Research' started by tom_ethansdad, May 9, 2016.

  1. tom_ethansdad

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    In a paper published in BMJ Open Diabetes Research & Care, researchers looked at the prevalence of type 1 diabetes in 118 countries and changes in life expectancy from 1950 to 2010.

    After applying a measure known as the Biological State Index to the data, they found that the rapid increase in type 1 diabetes over the last few decades was directly linked with increases in human life expectancy, especially in Western countries -- and therefore a reduction in natural selection.

    University of Adelaide. "Advances in medical care have led to type 1 diabetes boom." ScienceDaily. ScienceDaily, 5 May 2016. www.sciencedaily.com/releases/2016/05/160505104741.htm.
     
  2. rgcainmd

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    A great example of "You Can't Win for Losing" or "Damned if You Do and Damned if You Don't" if ever I saw one.

    Thanks for the link!
     
  3. Christopher

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    The conspiracy theorists are not going to like this one.


    :wink:
     
  4. Snowflake

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    I'm not a conspiracy theorist or an anti-vaxxer or anything of the sort, but I'm still not sure I get this. The study's conclusion seems premised on a much greater degree of heritability than T1D actually displays. I've met many, many T1 families, and I'd estimate that far fewer than 10% of the T1 kids have had a T1 parent or grandparent. Additionally, this doesn't account for the similarly increasing rates of associated autoimmune conditions that would not historically have been lethal before reproductive age (e.g., the doubling or quadrupling rates of celiac disease over the past 60 years, as demonstrated by stored blood samples).

    Admittedly, in addition to not being a conspiracy theorist, I'm also not a bio-statistician. It's an interesting parlor game, I'd love to read more!
     
  5. rgcainmd

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    I just hope a "Dia-Nazi" who believes that the "final solution" is to mandatorily sterilize all people with T1D doesn't come into power.

    I'm only half-joking.

    If Trump gets elected, he will likely propose that all U.S. citizens with T1D be immediately deported en masse...
     
  6. joshualevy

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    My general comment on this research: no question is answered by one study. Someday this study might be part of the answer to a question, but right now, it is just more data. Of course, most paper's I've seen arguing for an environmental cause to the recent increase start out with a statement like "the recent rise in type-1 is too large to be caused by genetics." They start out with this assumption and never try to support it at all. This paper is better than those papers, because it at least tries to answer the question.

    Remember that prior to about 1920, type-1 was generally fatal at onset, so no one should expect type-1 to be inherited in the simple minded way we all learned in high school. Think of it this way: genes are dice (each with a different color) and each person has dozens of them which impact type-1 diabetes. None of these dice say "if the red dice is 4 you get type-1". Rather they say things like "if the red dice is 4 your chance of getting type-1 goes up by 1%" or "if the light blue dice is 6 and the dark blue dice is 1, then your chance of getting type-1 goes up by 5% but only if the pink dice is not 1", and so on. Each person gets a bunch of dice from each parent, plus some random rolls, and then they grow up and some will get type-1. The "gene pool" is not specific genes that cause type-1, it is a mass of genes that raise or lower the chances.

    The argument is that in the modern world, the genes that generally increase the chance of type-1 are becoming more common, because those people used to die, but don't any more. (They are not arguing that one specific type-1 gene is becoming more common, because for autoimmune type-1, there is no one single gene that causes it. Off course, MODDY is different.)

    These researchers are saying that places with better health systems will have more type-1 genes in circulation and therefore more type-1. By comparing different countries with different health care systems, they can see that this effect is big enough to cover all the increase in type-1. It's a good research idea, but I'm not sure that -- by itself -- that kind of data will ever resolve the issue to everyone's satisfaction.

    I do think this is a reasonable objection to the conclusion. But the bottom line is that there is no where near enough information to settle the question either way right now.

    Joshua
     
  7. quiltinmom

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    Nice. At this point, honestly, nothing would truly surprise me. Sad to say.


    I don't take research like this very seriously. Basically all it means to me is that there are more people with diabetes because, before medical advances that keep them alive and well, they would've died within days or weeks of diagnosis. Duh. How much money did they spend to figure that out? Maybe they should have spent it to help poor children with type 1 get insulin instead. I don't think you can attribute such a complex thing to just one cause.

    Be what it may, I'll take it. I'd rather have a greater percentage of type 1s in our population than have them all be dead, whatever the cause. That extends to many other once-fatal diseases as well.
     
  8. sarahspins

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    I think if anything more diagnosis really has to do with more accurate diagnostic testing - think about how many young adults and adults (myself included) who were initially misdiagnosed because we were "too old" for T1. I had to fight to get an accurate diagnosis and I was only 20.... far too many patients don't question their doctors, and end up being misdiagnosed for years and years..
     
  9. Snowflake

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    Fair point. But my understanding is that the two big growing populations of newly diagnosed T1s are very young children (under age 5), see here http://health.usnews.com/health-new...-1-diabetes-up-70-percent-in-kids-study-finds , and adults like yourself. In young children at least, the symptoms are pretty obvious and dramatic, and very small children would be unlikely to survive years of mis-diagnosis.

    This researcher's hypothesis does not account (at least not directly) for changes in the age distribution at diagnosis. I think to be convincing, it needs to explain that also -- it's not just the incidence that's changing, but also the profile of the T1 population.

    As to why it matters: it'd be kind of cool in a way if this Australian researcher is correct, because it tells us that artificial insulin is doing its job, full stop. But if there's even a kernel of truth to any of the environmental/dietary hypotheses, then pediatricians might some day be able to offer practical advice about how to minimize risk for genetically susceptible kids. Having had two babies since my daughter's diagnosis, I gotta say it would have been nice if the pediatrician could have given advice like, "All you have to do is avoid [insert some random food or substance], and you'll reduce his risk of developing T1 by X%." But, like Joshua says, clarity on the reasons for the increasing rates seems to be a very long way off.
     
  10. joshualevy

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    I don't agree. I think the hypothesis can account for the younger diagnosis in a straightforward way: Assume that there are some genes that lead to early type-1 (between 0-10 years old) and other genes that leads to later type-1 (at 10 to 20 years old), plus a few other genes for even older. Before 1920, the 'younger' genes were weeded out of the gene pool entirely without exception, because no one has kids before then are 10. However, the 10 to 20 year old genes would have a few offspring. Because some people did have kids when they were in their late teens.

    So with the discovery of insulin, the people with "older" genes went from a small presence in the gene pool to a larger one. But the people with "younger" genes went from a really tiny presence to a larger one. So you can see why there would be a larger increase in the younger kids. (At least in theory.)

    Joshua Levy
     
  11. Christopher

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    Interesting topic. And sorry if this is a naive question but does science have a specific time frame that it takes for a specific gene to be "weeded out of the gene pool entirely without exception"?

    It is my belief that stem cell therapy/gene therapy will be the area of science that eventually finds a cure for Type 1 diabetes.
     
  12. samson

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    Not sure genetics can explain this.

    Joshua, that may account for some increase in the diabetic population over time, but not double over a 20-year span. In addition, a few studies suggest that those with "high-risk" T1D genes (such as the notorious HLA complexes, CTLA, PTPN22) have normal lifespan in comparison to others in the population, perhaps because they confer more robust infection-fighting properties to those who do not develop the disease, or perhaps because they have other benefits that make the people "fit" in other ways. So the genes themselves do not necessarily confer a reduced genetic fitness, which means natural selection would not act very strongly to eliminate these genes except in those who actually manifested the disease. Given that, and given that rates of T2D have also increased so markedly, it seems likelier that some common environmental trigger is causing dysregulation of sugar processing.I'm guessing epigenetic tags, which help regulate genes, may also play a role in who develops disease.

    Also, at least some of the increased prevalence is likely due to misdiagnosis or lack of diagnosis in the past. Little ones died off early and often in historical times, and sad to say most of their deaths were never "explained." Given that, it's also fair to assume that undeveloped countries are suffering from the same problem that historically afflicted all countries, and that their T1D cases and deaths are being underreported. There are also so many other differences between industrialized and developing nations (diet seems the obvious biggie) that I can't imagine how they are accounting for all those potential variables.

    Its really hard to evaluate this study's claims because all the articles I read about it were really terrible rehashes of the press release, and so their index wasn't even properly explained.
     
  13. joshualevy

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    No it doesn't, but the real problem is that I was sloppy in my language.

    I wasn't talking about weeding one gene out of the gene pool (because type-1 diabetes is not caused by one gene). Remember, it is a bunch of genes acting together that raise the chance of type-1 diabetes. So what I meant was that a gene collection which led to "young" type-1 onset would never be passed on. However, a gene collection which led to "late teen" type-1 onset might be passed on, sometimes. I'm talking about making a collection of genes less common in the population, not removing one specific gene entirely.

    Joshua Levy
     
  14. sgh

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    This study ignored all the existing research on the topic. I co-authored a letter to the editor of the journal about it and hopefully it will be published this week. Since it is not published yet I can't say much more than that now.
     
  15. joshualevy

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    When it is published, I hope you will either post it here, or tell us where it is on-line, so we can read it. Also, I always thought that letters to the editor were not covered by pre-publication blackouts.

    Joshua Levy
     
  16. sgh

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    I have no idea, and didn't want to risk it! yes, I will post it, but I haven't heard anything yet.
     
  17. sgh

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    letter

    OK the letter was accepted so I guess I can say more now! sorry it took so long, the journal apparently lost it! Now they have sent it to the authors to respond to so it still may be awhile till published.

    - These authors found a correlation between the "biological state index" (a measure that they designed to quantify reproductive success) and type 1 diabetes prevalence, which is the basis of their conclusion that natural selection is leading to an increasing genetic predisposition to type 1 in the general population (esp. Europe), which causes the increasing prevalence of type 1 diabetes. But as we know correlation is not causation. The correlation between these two items does not mean that natural selection is causing the increasing prevalence of type 1. It is pretty obvious that with insulin, people with type 1 will live longer (and just a longer life expectancy alone will increase type 1 prevalence). Natural selection does not necessarily follow from this correlation.

    - this study draws a huge conclusion and makes a giant leap from the correlation they found, but their conclusion contradicts all the existing research on the topic. These other studies are listed in my letter so I won't list them here. Yet the authors failed to cite ANY of this prior research! I consider that a scientific sin... they should have at least cited prior research and talked about why their results differed.

    - The other existing research studies are stronger than this study because they examined the genes of people who have developed type 1 (from multiple populations around the world). *All* of the other studies found that the high-risk genotypes associated with type 1 diabetes have actually decreased over the past decades, while more people with low-risk geneotypes are now developing the disease.

    - The authors did not look at incidence, which would be a much stronger metric to use than prevalence.

    - Almost 80% of people diagnosed with type 1 diabetes do not have any 1st or 2nd degree relatives with type 1 (also cited in letter).

    - I would also note that when I got pregnant in 1999, women with type 1 were still being advised to avoid pregnancy at times (and still today if BG isn't controlled). When people were diagnosed as children 40 years ago, their lifespan was predicted to be much shorter than today, perhaps discouraging them from having children. (I am thinking of people I know, diagnosed in childhood during the early 1980s, who (as I recall) were told that their predicted lifespan was about age 35... maybe I am not remembering correctly, but if I knew I might only live till 35, I would probably not have had children).

    - So while I do think it is entirely possible that natural selection could lead to an increase in type 1-related genetic predisposition in the future, with more and more of us type 1s successfully reproducing, as technology and treatment improves, most of the evidence (well, all of it, aside from this study) so far finds that the increasing rates of type 1 are more due to people with lower genetic risk developing type 1, not type 1 genes becoming more common.

    - I will post here when I hear what the authors have to say. The authors, by the way, are population researchers, not type 1 researchers. They do not have a background in type 1 research, and from their article, that seems pretty clear to me. My husband happens to have a PhD in biology/ecology and knows about population biology (and type 1!) and he helped me analyze the study and co-authored the letter with me. He could have addressed more of the population biology parts of the article but we decided to just focus the letter on the main issue. There are other problems with the article as well that we didn't get into, but it seems overall to be sorta a sloppy article (grammatical errors and so forth). (Although since the lead author may not be a native English speaker, that could explain the grammatical errors, so I don't want to be critical of that situation. But it seems the professor who is the 2nd author could have fixed it up a little...)

    Sarah
     
    Last edited: Jun 7, 2016
  18. rgcainmd

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    Sarah, thank you for posting (parts) of your well-written letter.

    There's nothing I hate more than poor science! How this study even made it to publication is beyond me...

    Keep us updated with any response from the "researchers" (I use the term loosely :rolleyes:).
     
  19. sgh

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    not sure it's well-written... lol

    anyhow I'm not sure if the original article was posted, this is it:
    http://drc.bmj.com/content/4/1/e000161.full

    when the letter is published there will be a link on the right under "responses." It's all free full text (which means, in this case, that the authors paid the journal to have this published.)
     
  20. Snowflake

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    Thanks for posting this. Very interesting!

    I hadn't seen this particular stat before, but it's interesting to have my anecdotal impression on this confirmed.
     

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