The Centers for Disease Control and Prevention (CDC) estimate that more than 29 million adults in the United States have diabetes. According to their 2014 National Diabetes Statistics report, around 11 percent of these people are women.
Recently, a study conducted by Drs. Taulant Muka and Eralda Asllanaj, both from the Erasmus University Medical Centre in the Netherlands, investigated the links between the natural onset of menopause and the risk of developing type 2 diabetes.
The study is published in the journal Diabetologia.
Unclear menopause-diabetes link
The basis for this research hails to a previous study by Dr. Muka and colleagues, which found that women whose menopause naturally sets in early - that is, before the age of 45 - are likelier to be diagnosed with cardiovascular disease (CVD) and are at a higher mortality risk.
Reports show that type 2 diabetes is an important risk factor for CVD, yet the links between early menopause and diabetes are still debatable. The new study aims to answer some of the questions surrounding this issue, taking a step forward in tackling diabetes risk in women.
The study analyzed data on 3,969 women sourced from the Rotterdam Study, the aim of which was to conduct research into the risk factors for various diseases and conditions among a large cohort of adults aged 45 and over. The participants underwent medical examinations once every 3 to 5 years.
The study defines as "postmenopausal" someone who has not menstruated in at least a year. To assess the women's status, questionnaires were distributed that asked them to report the age at which they experienced their last period.
Both newly diagnosed and previously diagnosed cases of type 2 diabetes were confirmed at the participants' baseline assessments, as well as in follow-up examinations. To this end, medical records, hospital discharge letters, and glucose level assessments were used. The study collected follow-up data until January 2012.
Early menopause correlates with diabetes
To identify factors with a potential impact on the overall findings, the researchers gathered additional data on the participants, including their baseline state of health, medical history, medication, age at menopause onset, physical activity levels, and whether they had been diagnosed with CVD.
Furthermore, since single nucleotide polymorphisms (SNPs), which are variations in a person's DNA sequence, are known factors for the early onset of menopause, genetic risk was also taken into account.
Out of the 3,639 women who did not have diabetes at the beginning of the study, 348 were diagnosed with type 2 diabetes during the follow-up period.
The researchers found that women who started menopause early (before age 40) were 3.7 times more likely to develop diabetes than women who started menopause later in life (between the ages of 45 and 55).
Women who had a normal onset of menopause (between ages 40 and 44) were at a slightly lower risk, but they were still more than twice as likely to be diagnosed with type 2 diabetes than their counterparts with late menopause onset.
In a previous study, Dr. Muka and colleagues had identified a link between diabetes risk, estradiol (the main female sex hormone) levels after menopause, and premature estrogen production owing to the start of menstruation at an early age.
In the same study, they also suggested that these factors might moderate the impact of early menopause on the risk of diabetes. However, their new research does not support this premise.
DNA might hold the key
Instead, the study found that the link between sex hormone levels, menopause, and diabetes did not explain the correlation between early menopause and risk of type 2 diabetes.
The researchers suggest that whatever may cause early menopause in some women might also be responsible for their predisposition to diabetes, hinting at hidden genetic factors. They say, "Our findings might suggest that the risk of diabetes related to menopause is already there before menopause begins."
"This could explain why other risk factors for diabetes do not explain the link between menopause and T2D [type 2 diabetes] - early menopause is an independent marker for T2D, indicating that something else is the driving force behind this observation, possibly defective DNA repair and maintenance."
However, they explain that further research is needed to test for possibilities and find more accurate answers.