Genetics and Early Life Influences

Recommendation: Start Prevention Early

Family history of type 2 diabetes is linked with an increased risk of developing the disease.1 If an immediate relative (a parent or sibling) has type 2 diabetes, you are considered at a higher risk of developing diabetes. Although many genetic variants have been associated with increased risk of developing type 2 diabetes, the effects of these genes are modest and explain only a small portion of diabetes cases. One major study, called the Diabetes Prevention Program, showed that even though genes were a risk factor for developing type 2 diabetes, making appropriate changes in one’s lifestyle decreased genetic risk.2
 
Where you grow up also influences your risk of developing diabetes. Exposure to environmental pollution and arsenic increases your risk.3 Risk often can increase among members of the same family because of their shared interaction with the same environment.
 
Asian women have double or triple the risk of white women of developing gestational diabetes.3 If a pregnant woman gets gestational diabetes, the child born is more likely to have a high birth weight, to be overweight in childhood, and to have impaired glucose tolerance during early adulthood. These are all factors that increase diabetes risk.4-10 This child, if a girl, may grow up to have gestational diabetes herself when pregnant, leading to a cycle of diabetes that must be broken through intervention.
 
Additionally, a mother who had gestational diabetes during pregnancy has nearly a 50 percent risk of developing type 2 diabetes for five years after giving birth.11 So, if you are a mother who has had gestational diabetes during the last five years, it is even more important that you monitor your diet and physical activity and get regularly screened for type 2 diabetes. Read more about gestational diabetes at our sister site, the Obesity Prevention Source.
 
If you are already pregnant, it is not advisable to go on a weight loss program, but it is important to prevent excessive weight gain during pregnancy. If you are planning on getting pregnant, losing excess fat and maintaining a healthy pre-pregnancy weight can decrease your risk of gestational diabetes and your child’s risk of type 2 diabetes later in life. Check with a health care professional before making any health decisions.
 
Moreover, there is a U-shaped relationship between birth weight and diabetes risk, indicating that a newborn with an abnormally low or high birth weight is at higher risk for diabetes.12 Based on studies relating birth weight to diabetes risk, 2.5 kg to 4 kg is the optimal range, and lower or higher than that range increases the risk of developing diabetes.13-14
 
A baby who is born or conceived during a time of famine may have increased risk of diabetes later in life as well. This is called the “thrifty phenotype” hypothesis.15 The theory is that a person’s metabolism upon birth has adapted to survive on fewer calories and in a nutritionally scarce environment, so when the environment changes as the person grows up, it has a negative effect on health. This has been shown through studies of people born in the Netherlands during a period of famine lasting from 1944 to 1945 and of people born in China during the severe famine that lasted from 1959 to 1961.16-17 If environmental and socioeconomic factors change so that a person born in famine experiences a much richer nutritional environment later in life, studies show there is an even greater risk of diabetes.11
 
References:
1 Ahlqvist E, Ahluwalia TS, Groop L. Genetics of type 2 diabetes. Clin Chem. 2011;57:241-254.
3 Chan JCN, Malik V, Jia W, et al. Diabetes in Asia: Epidemiology, Risk Factors, and Pathophysiology. JAMA. 2009;301(20):2129-2140.
4 Reece EA, Leguizamón G, Wiznitzer A. Gestational diabetes: the need for a common ground. Lancet. 2009;373:1789-1797.
6 Silverman BL, Metzger BE, Cho NH, Loeb CA. Impaired glucose tolerance in adolescent offspring of diabetic mothers: relationship to fetal hyperinsulinism. Diabetes Care. 1995;18:611-617.
7 Getahun D, Nath C, Ananth CV, Chavez MR, Smulian JC. Gestational diabetes in the United States: temporal trends 1989 through 2004. Am J Obstet Gynecol. 2008;198:525.e521-e525.
8 Dabelea D, Snell-Bergeon JK, Hartsfield CL, Bischoff KJ, Hamman RF, McDuffie RS. Increasing prevalence of gestational diabetes mellitus (GDM) over time and by birth cohort: Kaiser Permanente of Colorado GDM Screening Program. Diabetes Care. 2005;28:579-584.
10 Ferrara A, Kahn HS, Quesenberry CP, Riley C, Hedderson MM. An increase in the incidence of gestational diabetes mellitus: Northern California, 1991-2000. Obstet Gynecol. 2004;103:526-533.
11 Ley SH, Schulze MB, Hivert MF, Meigs JB, Hu FB. “Risk Factors for Type 2 Diabetes.” Diabetes in America. In press.
13 Harder T, Rodekamp E, Schellong K, Dudenhausen JW, Plagemann A. Birth weight and subsequent risk of type 2 diabetes: a meta-analysis. Am J Epidemiol. 2007;165:849-857.
14 Whincup PH, Kaye SJ, Owen CG, et al. Birth weight and risk of type 2 diabetes: a systematic review. JAMA. 2008;300:2886-2897.
15 Hu, FB. Globalization of diabetes: The role of diet, lifestyle, and genes. Diabetes Care. 2011;34(6):1249-1257.
16 Ravelli ACJ, van der Meulen JHP, Michels RPJ, et al. Glucose tolerance in adults after prenatal exposure to famine. Lancet. 1998;351:173-177.