To Breed or Not to Breed: the Genetic Risks of Diabetes

My grandmother was diagnosed with type 1 diabetes as an adult, a highly unusual occurrence back in the late 1940’s. As a child, I didn’t even know she had diabetes. I did know she always carried a Chunky in her purse. You remember those wonderful hunks of milk chocolate deliciousness. She used them to treat low blood sugar, although I always thought they were for me. Along with the occasional Chunky, she also passed along diabetes. I was diagnosed with type 1 when I was ten years old.

My grandmother developed diabetes after she was done having children. In contrast, I had ample time to think about my decision. Having a child is an irreversible, life-altering decision. Philosopher Christine Overall believes that deciding to have a child is the biggest ethical decision we will ever make. Indeed.

What Are the Odds?

The genetic risk of having a child with type 1 diabetes is not entirely understood and fluctuates greatly. If the father has type 1, the child has between a 6% and 8% chance of developing diabetes. If the mother has type 1, the risk can range from 2% to 3%. If both parents have type 1 diabetes, the risk increases to 25%. There are a number of contributing factors to explain the differences. The younger the parent was when diagnosed, being Caucasian, and the child having an early history of certain childhood traumas and infections increases the odds. The older the parent was when the child was born and the longer the mother breast fed decreases the odds. There are also environmental factors to consider such as living in a cold climate and early dietary variables that can impact risk.

The genetic risk associated with type 2 diabetes is also complex. If the father has type 2, the risk factor is about 30%, slightly higher if it is the mother. If both parents have diabetes, the risk factor jumps to about 70%. There are a number of factors that impact the risk, such as obesity, sedentary lifestyles, poor dietary practices, smoking, elevated blood pressure, and a history of gestational diabetes. All increase the risk.

The Times, They Are a Changing (with thanks to Bob Dylan)

My decision to have a child was not all about odds and statistics. I also addressed the issue of my child’s quality of life living with diabetes. I was discharged from the hospital on my eleventh birthday, 1966. My physician assured me there would be a cure within five years. He missed, several times over. My, oh my, did he miss. Just the same, I’ve seen some pretty impressive advances. I have experienced glass and disposable syringes, animal and analog insulin, urine and blood testing, continuous glucose monitors, and insulin pumps. The quality of my life has improved dramatically, and I believe I am handing off a future with great possibilities. I have to believe a cure is much closer than it was in 1966, when it was a mere five years away.

I’m Only Human

I’m also aware of some psychological influences on my decision making. Like most people, mine is curiously flawed. When dealing with personal issues, I can be unrealistically optimistic. Unrealistic optimism allows us to perceive ourselves and our situations favorably. This is not all bad as it helps us to feel better about ourselves, fend off depression, and deal with all those pesky life annoyances. It can also lead us to believe we can beat the odds, particularly when the odds are not overwhelming. If I am willing to believe that I can beat the odds of maintaining a successful marriage, I can certainly beat the odds that my child might develop diabetes.

Strange Bedfellows

I tend to be a bit academic. I like research, statistics, and psychology. But I found that none of this resulted in a formula to make this decision. My wife and I decided to have a child. It was a deeply personal, intuitive, and optimistic decision. He is now 27 years old and diabetes free. But I still worry. From the very beginning I was warned by his pediatrician not to overdo it testing his blood sugar every time he peed “too often”. With each passing year I have been thankful he hasn’t had to deal with diabetes. Not that he couldn’t, just that he didn’t need to. Ultimately, our decision to have a child was not academic. There were no guarantees, one way or the other. We just had to decide what was right for us.

5 Comments
    class="comment even thread-even depth-1" id="li-comment-4989">
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    It is also worth noting that the 1-2% of us with diabetes who have an autosomal dominant monogenic form (commonly referred to as “MODY”)have a 50% chance of passing along this gene and resulting diabetes to each of our children. As a physician, I diagnosed myself with diabetes in 1992 at age 33, joining my father, aunt and paternal grandfather. All of us developed diabetes as thin young adults in our 20s or early 30s. Once Type 1 had been ruled out for me, MODY became the prime suspect, and a MODY3 diagnosis was confirmed 6-7 years ago with genetic testing.

    My husband and I had already decided that having children was not for us, so my diabetes diagnosis and family history didn’t contribute to that decision. It did help to reconfirm it in some ways, however. I’m also grateful that my two siblings have not been affected by MODY, and that my four nieces and nephews are not at risk.

    For those interested in more information about MODY, I’d highly recommend an excellent 2015 review entitled “Undiagnosed MODY: Time for Action” (doi:10.1007/s11892-015-0681-7) that addresses the importance of genetic MODY diagnosis and provides a comprehensive summary of MODY epidemiology studies across diverse populations. Another superb article published in 2018, “Clinical Management of Women with MODY during Pregnancy” (https://doi.org/10.1007/s11892-018-0982-8), describes specific considerations related to maternal glycemic control, fetal mutation status, transplacental transfer of medications, and the need for large, prospective studies to better define management in this setting.

    Has TCOYD ever offered a professional education session on MOYD? If not, please consider doing so!

      class="comment byuser comment-author-lynne odd alt depth-2" id="li-comment-5001">

      Hi Dr. Baum,
      I don’t believe we’ve ever offered a professional education session on MOYD, but I will definitely share with Dr. Edelman and our continuing medical education team. Thank you for your comments and suggestion!

        class="comment even depth-3" id="li-comment-6639">
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        Dear Lynne,

        Thank you for your response and for sharing my request with Dr. Edelman and your CME team for TCOYD to consider offering professional education on MODY.

        I’m a big fan of TCOYD, having attended an extremely high quality TCOYD training here in Albuquerque a number of years ago that I found very helpful both personally and professionally. As a well-respected provider of diabetes education for both professionals and people living with diabetes, TCOYD would be perfectly positioned to increase awareness around the often missed diagnosis and appropriate management of MODY.

        Please let me know if there is any way I could contribute to TCOYD’s offering professional education on MODY, which I would consider an honor.

        Sincerely,
        Susan

    class="comment odd alt thread-odd thread-alt depth-1" id="li-comment-4990">

    My son was diagnosed at age 1, and now he and his fiancee bought a house and are contemplating kids. With a mother who is a researcher, he has access to genetic information, but this won’t stop them. He has a great life and career, and he watched this future grandma put his aab+ brother on a cocktail which derailed diagnosis. I hope all future moms take D3 and high dose O-3 and optimize the child’s AA/EPA ratios. See our study at grassrootshealth.net/t1d and read the stories at http://www.preventt1d.org. He also built his own APS – so can’t wait to hold future grandbabies! Oh, and we will bank cord blood along with protective supplementation…just in case….

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