As type 2 diabetes and obesity become more and more common, interest in finding causes and risk factors also increases. Children’s experiences increasingly seem to strongly affect their health later in life. Now research shows that the timing of puberty is very closely associated with men’s risk of developing type 2 diabetes later in life. The risk of developing type 2 diabetes earlier in adulthood was almost doubled among boys experiencing early puberty versus late puberty.
In the past 30 years, the prevalence of type 2 diabetes has increased 10-fold, with more than 5% of the global population being diagnosed. The reasons are many, but a strong consensus maintains that one of the greatest risk factors is changing lifestyles with too much food and too little exercise. Now researchers have found a new risk factor that is associated with a significant increase in men’s risk of type 2 diabetes.
“Our new study shows that the timing of puberty is an important indicator of whether men develop type 2 diabetes or not. Boys who have their maximum growth spurt at age 9–13 years have double the risk of developing type 2 diabetes earlier compared with those who enter puberty at 15–18 years old. This is important knowledge that doctors should consider when assessing men’s risk of developing type 2 diabetes in middle age,” explains a leader of the project, Jenny Kindblom, Associate Professor, Sahlgrenska Academy, University of Gothenburg.
Most rapid growth
The new study included 30,697 men in Sweden born between 1945 and 1961. The data came from the BMI Epidemiology Study Gothenburg, a population-based epidemiological study, which included data on height and weight in childhood from the school health services and surveys of conscripts. The study included data on children’s age when entering puberty and BMI before and after puberty.
“Today, we can determine who developed type 2 diabetes and who did not from the Swedish National Patient Registry. Overall, 1851 cases of type 2 diabetes were diagnosed (6%) before the follow-up period ended. The median age when type 2 diabetes was diagnosed was just over 57 years,” says Jenny Kindblom.
Girls’ puberty is clearly defined based on their first menstruation, but easily available indicators are lacking for boys. However, the change in height of the boys quite precisely determines when puberty begins –when boys grow most rapidly. In this study, the mean age for this was 14 years old.
“The strongest association was between early puberty and being diagnosed with type 2 diabetes earlier than the average age of 57 years. For the quarter of the participants who had entered puberty at 9–13 years, the risk of developing type 2 diabetes was twice as great as those who entered puberty at 15–18 years old,” explains Jenny Kindblom.
Adolescence can increase adult mortality
Jenny Kindblom and Claes Ohlsson are leading researchers in the large population-based BMI Epidemiology Study Gothenburg, of which this study is part. The purpose is to determine how height, weight, BMI and puberty in childhood influence the development of diseases such as cardiovascular and metabolic diseases, cancer and bone fractures later in life. The Study made an important discovery as early as 2009.
“We found that adolescents who gained too much weight as teenagers tended to have more visceral fat –fat around the organs – and this is a risk factor for heart disease later in life. These results, like the new ones, showed that adolescence is crucial to health later in life,” says Jenny Kindblom.
Why this is true is still unknown. The researchers suspect the long-term effects of hormones such as testosterone that increase at puberty. Regardless of the reason, the researchers think that men’s early puberty should be considered a new and independent risk factor for developing type 2 diabetes.
“The risk is clearly higher among those who entered puberty early, and an estimated 15% of the men diagnosed with type 2 diabetes during the study would not have developed it if they had not reached puberty so early. To identify and help more people, continually monitoring height and weight is important – not only in early childhood but also in adolescence,” explains Jenny Kindblom.
“Early puberty and risk for type 2 diabetes in men” has been published in Diabetologia. In 2016, the Novo Nordisk Foundation awarded a grant to co-author Claes Ohlsson, Professor, Sahlgrenska Academy, University of Gothenburg, for the project Personalized Anti-fracture Treatment.