November is National Diabetes Awareness Month. Dana Dabelea, MD, PhD is co-chair of the SEARCH for Diabetes in Youth study and currently the principal investigator on nine federally funded grants. She is also the director of the Center for Lifecourse Epidemiology of Adiposity and Diabetes (or LEAD) and an active educator for students and fellows. This week on Our Milky Way, she shares fascinating and valuable insight on how infant feeding plays a role in diabetes outcomes.
Q: How did you become interested in maternal child health?
A: I was trained as an internist and diabetologist in Romania and worked primarily with adults, though I did see youth with type 1 diabetes. I later became a fellow at the Epidemiology and Field Studies Branch of the National Institutes of Health in Phoenix, Arizona. There, we noticed that young American Indian children were developing diabetes that used to be seen only in adults – namely Type 2 diabetes. Since they were young (some as young as age 5) it seemed logical that something was happening very early in life that set them on this trajectory. We began to study the effect of having diabetes during pregnancy – called gestational diabetes or GDM – on the offspring of those pregnancies. It turned out that the recent rise in youth onset type 2 we had been seeing was almost completely explained by the increase in GDM among mothers. The realization that early life events had later consequences was what really got me started in this area.
Q: To date, what is your most fascinating discovery?
A: After our studies in Arizona, we showed in Denver that the effect of GDM was very similar among non-American Indian youth. That and other studies led us to ask what GDM does to the offspring to increase the risk of diabetes and obesity – we knew from Arizona studies that while genetics plays a small role, something was very specific to pregnancy. So I began a study of pregnant mothers and their offspring called Healthy Start that collects information from the mothers and children as well as biologic samples to study this question. We began studying fuels that fed the growing baby – such as fats of various types and sugars- all of which come through the placenta and umbilical cord to nourish the fetus. It turns out that fatter babies (measured with an instrument called the PedPod®) had mothers with higher glucose levels during pregnancy, even if these levels were still considered in the “normal” range. We followed the offspring and looked at what influence postnatal feeding had as well. It turns out that breast-feeding for at least 6 months largely reverses the effects of GDM on fatness in children. I think this was exciting, since it meant that there are things that can be done very early in life that can reduce the later risk of obesity and diabetes. We continue to look for others. But there is one additional thing of great interest – in studies of stem cells grown from the umbilical cords of these babies by my basic science colleagues, they have shown that obese mothers unknowingly ‘program’ these stem cells to be more likely to turn into fat cells than muscle or bone cells – some of the first human evidence of a possible pathway that changes how an infant responds to their environment. This too is very fascinating!
Q: The SEARCH for Diabetes in Youth study has shown diabetes to disproportionately affect minority children. Can you please briefly discuss this health disparity?
A: You are correct for type 2 diabetes – that used to be called adult onset diabetes. Type 1 diabetes (juvenile diabetes) is actually most common among non-Hispanic white youth, although recently we are seeing increasing trends in minority group, especially Hispanics. There are several factors at work in type 2 diabetes, but we don’t yet know all of the story. First, a higher proportion of minority youth are overweight or obese, which is the major risk factor for later diabetes. Second, many of these are children are offspring of mothers who themselves have diabetes, GDM, or even just obesity as they enter pregnancy. Such women pass to their babies an increased susceptibility for obesity and diabetes, a phenomenon called the “vicious cycle” – where the risk of obesity and diabetes are passed to the next generation without involving genetics. Lack of breastfeeding, or only a short duration of breastfeeding likely also plays a role, since it appears that breastfeeding reduces both obesity and diabetes among offspring. There is likely also increased genetic among minorities, which is actively under study.
Q: It’s been found that research takes about 17 years before it’s integrated into policy and practice. Are you concerned about this phenomenon as it relates to the diabetes epidemic among youth in the U.S.?
A: It would be great if we could move more quickly from basic and epidemiologic research into public health and clinical action – and there has been progress in this area. Fueled by a National Institutes of Health funding strategy called “Clinical Translational Sciences Awards” to many institutions across the country, these awards specifically target moving science from the “bench” to “bedside” (clinical action) to the community (public health action). A factor that still affects the time to answers and action is that our epidemiologic studies of mother-child populations need to follow participants as they grow up to see what is happening. Thus, we may have a good guess (hypothesis) about what is happening, but it may take several years of follow-up to learn if we were right. This is also true of prevention efforts aimed at obesity and diabetes. Recent data suggest that the obesity epidemic may be leveling off, but whether this will last, or even reduce diabetes, remains unknown. So there is an inherent delay while the studies are being completed.
We can still recommend and test best practices as we know them today, even with incomplete knowledge. For example, we conducted a pilot randomized controlled trial of obesity prevention among American Indian children aged 7 to 10, called Tribal Turning Point. We found that a combination of parent-child sessions aimed at behavioral motivation for change, along with a toolbox of community activities, cooking classes and fun things for kids to do, resulted in lower weight gain among the group that got the intervention. We are expanding this study to both urban and rural American Indians with a larger sample size to see if we can replicate the results. This kind of work is aimed at helping stem the tide of the epidemic in the highest risk group – American Indians. But counter forces are strong – an abundance of calories, often of poor quality, the ease with which we can live without much physical activity and potential environmental factors such as air pollution and endocrine disrupting chemicals, are all promoting dangerous levels of obesity.
Q: Can you please explain the term transgenerational prevention strategy? How does infant feeding fit into this dialogue?
A: I mentioned the “vicious cycle” of transgenerational obesity and diabetes above. Let me explain this in terms of prevention. We know that mother’s obesity prior to pregnancy, her amount of weight gain during pregnancy, and whether or not she develops diabetes during pregnancy, all increase the risk of obesity in the next generation – her offspring. There is even data suggesting that this risk may be partially transmitted to her grandchildren as well. So any preventive intervention aimed at reducing maternal obesity, weight gain or GDM during pregnancy all have the potential to be trans-generationally preventive.
Infant breastfeeding is one important component of this strategy. As I mentioned previously, we found that breastfeeding greatly reduced the risk of obesity in the offspring, brought about from the mother developing GDM. One caveat – this is from observational data, and it really needs to be tested in a clinical trial before saying that we really know this works.
Q: You have found that “breastfeeding ameliorates increased adiposity of offspring born to mothers with gestational diabetes.” Is this due to the act of breastfeeding itself or the components of human milk? Both?
A: These are good questions. While I suspect that it is largely due to breastmilk components, there is limited data on this as it relates to obesity and diabetes prevention. The reason I suspect this is that banked breast milk appears to provide similar benefits. But again, this is largely my opinion at this point in time.
Q: Does the duration of breastfeeding seem to have an effect on diabetes prevention? How about exclusivity?
A: I think both are important. In our studies we calculate “breast-milk-months’. If a woman breastfeeds exclusively for three months, then breastfeeds about one-half time for the next six months, we call that six breast-milk months, since (exclusive X 3) + (1/2 time X 6) = (3 + 3) = 6 breast milk months. There are other combinations that also produce six or more breast-milk months. I think this helps mothers who have trouble continuing breast feeding exclusively on return to work or for other reasons, but continuing for longer at part-time appears to provide at least many of the benefits as they relate to obesity
Q: How does the introduction of complementary feeding affect diabetes outcomes?
A: A number of studies of the timing of introduction of cereals, cow’s milk, formula, and other solid foods, have been conducted in children at genetically high risk of developing type 1 diabetes. Summarized simply, since this is a complex set of studies, it appears that introduction of cereals or any solid food before 4 months increases the risk of type 1, and similarly introduction at six months or after of either of these also appears to increase risk. Importantly, introduction of cereals at or after six months while breastfeeding actually reduces risk. It is important to remember that these studies were done among children who are at high genetic risk for type 1, and it is not clear that these findings are true among most children who are not already at increased risk.
I am not aware of studies that have rigorously tested this for type 2 diabetes. However, early introduction of solid foods (before six months) have been associated with increased fatness and obesity in children.
Q: The U.S. has the worst maternal mortality rate in the developed world, and our infant mortality rate is deplorable too. What’s more, lactation and breastfeeding education, promotion, protection and support are severely lacking. Even so, are there noteworthy efforts you’d like to highlight that aim to resolve these tragic outcomes?
A: I think the most notable efforts started with Dr. David Olds here at the University of Colorado. A number of years ago his team began the Nurse-Family Partnership (also called the Nurse Home Visiting Program) where a nurse visits high risk pregnant mothers who may lack access to pregnancy care, may suffer from poverty, teen pregnancy, and other risk factors, and works with the mother (and father, if available) to teach them about healthy pregnancies and how to nurture their infant after birth, including breastfeeding assistance. This intervention has been tested in rigorous clinical trials in several US and international settings and has shown marked improvements in infant outcomes over many years. Today, Nurse-Family Partnership serves low-income, first-time moms and their babies in 42 states, the U.S. Virgin Islands and six Tribal communities. I believe the widespread utilization of this approach would go a long way toward improving both maternal and infant mortality and would increase breastfeeding.