Many published medical studies are based on data from hundreds, sometimes thousands, of subjects. For this new study, however, the researchers, who were led by Natalie Nanyakkara, PhD, and Sophia Zoungas, PhD, of Monash University in Melbourne, Australia, used online databases to collect data on 1.3 million people. They utilized 26 observational studies that included subjects from 30 countries in Europe, North America and Asia, and, when necessary, they contacted the authors of the studies by e-mail in order to reanalyze the data and present it in a homogeneous format. The average age of the subjects ranged from 21.6 to 67.4, while the proportion of the subjects who were female ranged from 42.5% to 68.6%, depending on the study.
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After crunching the numbers, the researchers determined that the older the age at which a person was diagnosed with diabetes, the lower that person’s risk of dying from all causes (all-cause mortality). They also found that the older people were less likely to develop macrovascular and microvascular disease complications (macrovascular complications include stroke, heart disease and peripheral arterial disease; microvascular complications include neuropathy, retinopathy and kidney disease). Specifically, the researchers found that for every year by which a diabetes diagnosis was delayed, the risk of all-cause mortality was lowered by 4%, the risk of macrovascular disease was lowered by 3%, and the risk of microvascular disease was lowered by 5%. “While earlier studies,” the authors wrote, “have assessed the effects of age at diabetes diagnosis on diabetes complications, to our knowledge, this is the first systematic review and meta-analysis exploring associations between age at diabetes diagnosis and subsequent outcomes.”
The authors acknowledged that people who are diagnosed with diabetes at an older age are more likely to have developed cardiovascular risk factors than people who are diagnosed at a younger age. But, they said that over time, “the effects of aging and disease duration may be amplified, resulting in premature complications and death in people diagnosed with type 2 diabetes at a younger age.” As an example, they observed that a person diagnosed with diabetes at age 30 is less likely to have diabetes complications at the time of diagnosis than a person diagnosed at age 50. When both of these patients, however, reach 60, the one diagnosed at a younger age would have a higher risk of complications and death.
The new findings are considered especially important because diabetes rates are increasing at a disturbing rate among younger people. Late last year, for example, the U.S. Centers for Disease Control (CDC) reported that between 2002 and 2015 the rate of new cases of diabetes in people under 20 increased in the United States, with a 4.8% increase each year for type 2 diabetes and a 1.9% increase every year for type 1. The message of the study, therefore, is clear: Medical personnel need to be vigilant about treating younger patients. As the researchers wrote, “younger people pose a significant challenge for clinicians and decision makers who need to be aware of these compounding pathologies of natural aging and premature vascular aging associated with type 2 diabetes. Further, people diagnosed with type 2 diabetes at a younger age still have the potential to develop complications at an earlier stage of life, at a time when the complications are more likely to cause greater disability and loss of productivity when compared with people diagnosed at an older age.”