Early Type 2 Diabetes Predictions Unveiled

New insights unveiled at this year’s European Congress on Obesity (ECO) in Venice, Italy (12-15 May) and disclosed in Diabetologia indicate that the conjunction of low birthweight and overweight during young adulthood, rather than childhood, significantly contributes to the onset of type 2 diabetes at an early age (59 years or younger) in men. Remarkably, the investigation, encompassing over 34,000 Swedish males, divulged that individuals born with a low birthweight (< 2.5 kg/5 lbs 8oz) who were overweight at the age of 20 years (BMI > 25kg/m²) were tenfold more prone to developing early type 2 diabetes than those with a birthweight within the normal range (2.5-4.5 kg) who maintained a normal weight as young adults (BMI < 25 kg/m²).

Significantly, the scholars from the University of Gothenburg and Sahlgrenska University Hospital also noted that infants with a low birthweight who were overweight at the age of 20 years faced a 27% absolute risk of developing early diabets mellitus, compared to a 6% absolute risk for those with a birthweight within the normal range who remained of normal weight at the age of 20 years. This underscores the potential reduction in the absolute risk of type 2 diabetes by 21% through the prevention of excessive weight gain during young adulthood in boys born with a low birthweight.

The diagnosis of this condition is increasingly occurring at younger ages, implying that significant risk factors may start accumulating during the developmental phase. Although the connection between low birthweight and overweight during childhood and/or young adulthood and type 2 diabetes in adults has been acknowledged, the degree of influence exerted by the combination of these factors has remained unclear.

To delve deeper into this issue, researchers analyzed data from 34,231 men born between 1945 and 1961 participating in the BMI Epidemiology Study (BEST) Gothenburg—a population-based cohort investigating the associations between growth and BMI development in early life and the risk of disease in later life.

The investigators examined the birthweight and BMI of participants using school health care records (at the age of 8 years) and medical examinations upon military enrollment (at the age of 20), which was mandatory until 2010.

Participants were monitored from the age of 30 until the diagnosis of this condition, death, emigration, or until December 31, 2019. Data on type 2 diabetes diagnoses were gathered from Swedish national registers to assess the risk of early (< 59.4 years) and late (> 59.4 years) type 2 diabetes. They also investigated whether these associations were independent of, or modified by, socioeconomic factors such as education level.

Over an average follow-up period of 34 years (after the age of 30), a total of 2,733 cases of type 2 diabetes were diagnosed (1,367 cases of early diabetes and 1,366 cases of late diabetes). The analyses revealed that birthweight below the median (< 3.6 kg/7lbs 9oz) and overweight at the age of 20 years (BMI > 25 kg/m²), but not overweight at the age of 8 years (BMI > 17.9 kg/m²), were linked with an elevated risk of both early and late diabetes.

Furthermore, low birthweight and overweight during young adulthood were found to have a cumulative effect on the risk of type 2 diabetes. For instance, individuals with a birthweight below the median (< 3.6 kg/7lbs 9oz), followed by overweight at the age of 20 years, faced a six-fold increased risk of developing early onset of this diabetes. Conversely, a lower birthweight (< 2.5 kg/5 lbs 8oz) combined with later overweight at the age of 20 years was associated with a ten-fold greater risk of developing early type 2 diabetes.

Adjustments for education, a recognized risk factor for type, had minimal impact on the findings.

“Our findings establish low birthweight and overweight during young adulthood as primary developmental determinants, while overweight during childhood holds lesser significance for type 2 diabetes in adult males,” remarks lead author Dr. Jimmy Celind, a researcher at the Institute of Medicine, Sahlgrenska Academy, University of Gothenburg. “The combination of low birthweight followed by overweight at the age of 20 years is linked with a substantial excess risk for early onset of diabetes mellitus, significantly surpassing the risk associated with low birthweight or being overweight as a young adult individually.”

Co-author Dr. Jenny Kindblom from Sahlgrenska University Hospital adds, “The metabolic ramifications of fetal growth restriction, which fosters resilience against starvation through fat storage and insulin resistance, possibly combined with a detrimental BMI trajectory during puberty when insulin resistance peaks due to the surge of growth and sex hormones, may result in an additive excess risk for later type 2 diabetes. Public health initiatives should target boys born with low birthweight to prevent overweight during young adulthood and mitigate this significant excess risk for early type 2 diabetes.”

The authors acknowledge that the findings represent associations only and that the study wasn’t designed to ascertain direct cause and effect. They also highlight several limitations, including the predominantly white male participants, which may limit the generalizability of the findings to other ethnicities and females. Additionally, the analyses were unable to account for the influence of other recognized risk factors for type 2 diabetes such as smoking, dietary habits, and physical activity, which could have influenced the results.