Mortality Risk in Type 1 Diabetes

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Glycemic control plays an important role in preventing death in type 1 diabetes.
Glycemic control plays an important role in preventing death in type 1 diabetes.

Last summer, Chiang and colleagues published a 20-page article on the management of patients with type 1 diabetes. This publication provided valuable information from research to glycemic goals among this population. For more and specific information, I'll refer you to the full paper.1

I was thinking about this publication and then also thought back to a November 2014 publication in New England Journal of Medicine about glycemic control and risk for mortality among patients with type 1 diabetes.2

Using the National Diabetes Register in Sweden, patients were identified as cases between January 1, 1998, and December 31, 2011, using the following criteria: insulin treatment and diagnosis before age 30 years. For each case identified in the register, five unregistered controls were identified and matched based on several factors, such as age and gender. The final results were 33,915 cases and 169,249 controls.

The primary endpoints were all-cause and cardiovascular (CV) mortality, reported as number of events per 1,000 patient-years. In addition, the primary endpoints were also linked to albuminuria and stage 5 chronic kidney disease to determine the risk for death or death from a CV event. 

From the cases, approximately 45.1% were female with a mean age of 35.8 years and 20.4-year history of diabetes. Among these patients, average HbA1c was 8.25%. Cases had adequately controlled mean blood pressure values and low history of CV conditions (acute myocardial infarction, 2.2%; coronary heart disease, 4.3%; stroke, 1.5%). Approximately 13.6% of cases were smokers with the highest prevalence among cases with HbA1c above 9.7% (23.4%).

Based on these results, the study confirmed that a higher HbA1c is linked to a greater risk for all-cause mortality, CV mortality and diabetes-related mortality. Among all cases, patients with type 1 diabetes had hazard ratios (HRs) of 9.97, 3.42 and 3.37 for all-cause mortality, CV mortality and diabetes-related mortality, respectively.  Cases with HbA1c levels above 9.7% had the highest risk for these endpoints (HR, 16.25, all-cause mortality; 4.73, CV mortality; 7.28, diabetes-related mortality).

All cases and controls were stratified based on age and gender; there was a significantly higher risk for primary endpoints, no matter what age group (older than 18 years of age) and gender (P<.001 for all stratifications, compared with controls).

It is important to note control of risk factors from the study. Approximately 43.1% and 39.7% of the cases were prescribed a statin and angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB), respectively.

Overall, this study adds to the large pool of literature regarding glycemic control and risk for mortality. For patients with type 2 diabetes, these individuals are often overweight or obese with hypertension and hyperlipidemia. It is important to control risk factors with statins, aspirin and ACE inhibitors (or ARB). 

For patients with type 1 diabetes, these individuals are typically slimmer and may not have hypertension or hyperlipidemia. This study still concludes that glycemic control, particularly an HbA1c above goal, can increase the risk for all-cause mortality and CV mortality. Therefore, it is important to adjust basal-bolus regimen among patients with type 1 diabetes to obtain tighter glycemic control, as tolerated.

References

  1. Chiang JL et al. Diabetes Care. 2014;37(7):2034-2054.
  2. Lind M et al. N Engl J Med. 2014;371:1972-1982.
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