HAMBURG, GERMANY – , shows a longitudinal study looking at comorbidities both 25 years before and 25 years after a type 2 diabetes diagnosis.
About 40% of people had respiratory tract infections at the time of diagnosis with type 2 diabetes, compared with 4% who were not diagnosed. Likewise, ear, nose, and throat infections were present in 20% of people at type 2 diabetes diagnosis, compared with around 2% who were not diagnosed. A similar pattern was seen with asthma.
Taken together, the data suggest that subacute inflammation manifesting in asthma as well as the onset of asthma or an acute infection may be a precursor to a type 2 diabetes diagnosis.
“We have also found that in the years prior to diagnosis, there are associations with infections and inflammatory disorders to a much greater degree than in those people who do not get a diabetes diagnosis but who have very similar demographics,” Adrian Heald, MD, study lead and diabetes consultant from Salford (England) Royal Hospital, said in an interview.
Five years prior to diagnosis, respiratory tract infections were documented in around 23% of patients who were later diagnosed with type 2 diabetes versus 2.5% in those not diagnosed, and a similar pattern was seen for ear, nose, and throat infections and asthma. The findings suggest that patients reporting infections, in addition to other known risk factors for type 2 diabetes, might benefit from diabetes tests and early interventions, if needed.
“These novel insights offer a fascinating and fresh perspective on the onset and natural progression to type 2 diabetes and beyond, suggesting an early phase of inflammation-related disease activity long before any clinical diagnosis of type 2 diabetes is made.”
Dr. Heald points out that clinicians may intervene to stave off progression to a type 2 diabetes diagnosis in at risk patients. “At this point, an intervention could relate to lifestyle changes and involve highlighting to the patient that the morbidity they have already accumulated is suggestive of diabetes risk,” he said, adding that, “they may have dyslipidemia, hypertension, and most often excess weight so annual checks of their HbA1c, weight management, and blood pressure would need checking,” he explained.
Moderator Coen Stehouwer, MD, professor of internal medicine at Maastricht University, the Netherlands, commented, “Before clinical diagnosis of type 2 diabetes there is often a lengthy period of undiagnosed disease and before that, prediabetes, because glucose can be abnormal up to 10 years prior to clinical diagnosis.”
But he added that, “It’s not entirely clear whether the rise seen before clinical diagnosis in this study correlates with undiagnosed diabetes or prediabetes or even if it precedes type 2 diabetes – it might be because inflammation is a common origin for type 2 diabetes and various comorbidities. This might explain how they go together.”
Longitudinal study 25 years before and 25 years after type 2 diagnosis
Dr. Heald presented the findings at a session on inflammation in diabetes at the annual meeting of the European Association for the Study of Diabetes. The work was also published in Diabetes Therapy.
The researchers wanted to investigate the pattern of comorbidities in the years and decades prior to a diagnosis of type 2 diabetes as well as after: “With the database we used, called DARE [Diabetes Alliance for Research in England], we are able to explore phenomena longitudinally going right back to the beginning of their digital health records, looking at phenotypes over time.”
By mapping significant health issues in people who went on to develop type 2 diabetes alongside those that did not, Dr. Heald managed to develop a continuum spanning 25 years prior and 25 years after diagnosis of type 2 diabetes. The researchers also examined relationships between sociodemographic factors and longitudinal health outcomes of relevance to cardiac conditions and lower respiratory tract infections. His talk in Hamburg primarily addressed clinical phenotypes before the point of diagnosis.
Data were drawn from 1,932 people with (1,196) and without (736) type 2 diabetes. Participants in both groups were aged 66-67 years, 43%-46% were women, age at diagnosis was 50-52 years, and participants lived in Greater Manchester, United Kingdom.
In the years leading up to type 2 diagnosis, individuals consistently exhibited a considerable increase in several clinical phenotypes, reported Dr. Heald. Of note, he added, “immediately prior to type 2 diagnosis, there was a significantly greater proportion of hypertension at 35%, respiratory tract infection at 34%, heart disease at 17%, ear, nose, and throat infection at 19%, and asthma at 12%. And by comparison, the corresponding disease trajectory in matched controls was much less dramatic.”
“There is a huge difference in people who went on to receive a diagnosis of type 2 diabetes and those who did not, and not just what we’d expect – so hypertension for example or manifestations of renal disease, but importantly inflammatory disorders are more common,” he emphasized.
In addition, a larger signal for ischemic heart disease was seen just before type 2 diabetes diagnosis.
These data suggest that longitudinal clinical histories prior to a diagnosis of type 2 diabetes might offer new information, both genetic and nongenetic, about development of type 2 diabetes in relation to comorbidities.
After type 2 diabetes diagnosis, the proportion of people exhibiting coronary artery disease, hypertension, chronic kidney disease, retinopathy, and infections climbed rapidly before plateauing, reported Dr. Heald. “We also know that individuals with coronary artery disease are more highly represented in socially disadvantaged groups, and this is borne out in the data at 25 years prior and after type 2 diagnosis.”
Dr. Heald has received speaker fees or contributed to advisory boards from Lilly, AstraZeneca, Janssen, Bristol-Myers Squibb, Besins, Bayer, Sanofi, and Recordati. Research grants from Novo Nordisk, Pfizer, and Besins. Professor Stehouwer has declared no relevant conflicts.
A version of this article first appeared on Medscape.com.