Multimorbidity is common for people with type II diabetes (T2D) with around 85% suffering from other chronic conditions. Comorbidity could make it more difficult to maintain inadequate control of blood glucose leading to further complications of diabetes, such as foot ulcers. The relative risks imposed on diabetics by comorbid conditions are not currently quantified by a universally accepted measure. Glycated haemoglobin (HbA1c), an indicator of glucose control over the long term, could inform the severity of comorbid conditions and thus the risk of mortality in type II diabetics.
Frances S. Mair of University of Glasgow, UK, and colleagues investigated the associations between the number of comorbidities, HbA1c level and all-cause mortality in people with T2D enrolled in UK biobank and Taiwan National Diabetes Care Management Program (NDCMP). The results were published in the journal PLoS Medicine.
From the UK biobank 20,569 participants with T2D were included and 59,657 people from the Taiwan NDCMP. Morbidity was classified into 42 chronic conditions in addition to T2D. In the UK Biobank, more than 90% of participants had at least one chronic condition in addition to T2D compared with around 80% of those in the Taiwan NDCMP.
Hypertension, pain, coronary heart disease, indigestion, and chronic liver disease were the most common comorbidities in the two datasets. Interestingly, overall the HbA1c levels were inversely associated with the number of comorbidities. With more comorbidities the risk of mortality was significantly greater. In the UK biobank heart failure, peripheral vascular disease, alcohol problems, and atrial fibrillation were the most risky comorbidities. In the Taiwan NDCMP cancer, heart failure, chronic kidney disease, and viral hepatitis were the most risky comorbidities.
Higher HbA1c is normally associated with poor glucose control which might be expected for multimorbid T2D patients, however those who live with more chronic conditions may receive more intensive care and be more rigorous in their diabetes treatment regimen. Another possibility is that medications for conditions that are commonly comorbid in T2D have a direct effect on HbA1c. Such possibilities were not addressed by the study.
“In conclusion, increasing multimorbidity is significantly associated with increased mortality in those with T2D and with lower HbA1c. This was observed in two large community cohorts of people from different healthcare systems. The highest risk of mortality is seen in those with concordant conditions, but discordant conditions such as alcohol problems, chronic liver disease, and COPD in UK Biobank and cancer and viral hepatitis in the Taiwan NDCMP cohort were still associated with more than 2-fold the risk of mortality,” stated the authors.