Type 1 Diabetes in Adults: A Consensus Statement From the American Diabetes Association and European Association for the Study of Diabetes

Type 1 diabetes occurs at any age and can be misdiagnosed as type 2 diabetes in adults. Better testing methods and professional education are needed.

A joint consensus report from the American Diabetes Association (ADA) and European Association for the Study of Diabetes (EASD) on type 1 diabetes (T1D) in adults says health care professionals worldwide need more awareness, education, and guidance in diagnosing and treating the disease. The consensus report was jointly published in the journals Diabetologia and Diabetes Care.

“The EASD and ADA have both recognized the ongoing challenges and an increased awareness of the psychosocial burden of living with type 1 diabetes, together with the rapid development of new treatments and technologies to deliver insulin and monitor blood glucose,” Dr Richard Holt, Professor in Diabetes and Endocrinology at the University of Southampton, United Kingdom told Endocrinology Advisor.  “Although we were aware of both national and international guidance on type 1 diabetes, much of this is contained within documents about type 2 diabetes and may not be apparent to practicing healthcare professionals.”

Dr Holt is one of the authors and co-chair of the consensus report, along with Dr Anne Louise Peters, Professor of Medicine at the Keck School of Medicine of the University of Southern California and Director of the University’s Clinical Diabetes Programs. Many other international researchers also contributed to the report, and it was acknowledged that it represented only the authors’ opinions.

The report, according to Dr Holt, was not intended to duplicate national and international guidelines on T1D diabetes already in existence.

“We did not seek to replicate this guidance, but rather aimed to highlight the major areas of care that health care professionals should consider when managing adults with type 1 diabetes in [a] single report,” Dr Holt said, adding that “the EASD-ADA consensus report on the management of hyperglycemia in type 2 diabetes has been hugely influential and has improved the care of people living with type 2 diabetes. With this report, we hope to do the same for people living with type 1 diabetes.”

Although it is widely accepted that the discovery and availability of insulin has revolutionized diabetes care, there remains a high level of burden on T1D patients, both medical and psychological, according to the report. It is important for physicians to be knowledgeable about advances in the diagnosis and the treatment of T1D to maintain high levels of patient care across the United States and European Union.

Dr Richard Holt, Professor in Diabetes and Endocrinology at the University of Southampton, United Kingdom

“Misclassification of T1D in adults is common and more than 40% of those developing type 1 diabetes after age 30 years are initially treated as having type 2 diabetes [because type 2 diabetes is more common among that age group]”, Dr Holt said.

”Furthermore, other forms of diabetes, such as monogenic diabetes, can be misdiagnosed as type 1 diabetes,” Dr Holt added. “This is important because it means that people experience delays in receiving the treatment they need. At worst, people could die from diabetic ketoacidosis if type 1 diabetes is missed. 1 Misdiagnosis can also erode the confidence people with new-onset type 1 diabetes have in their healthcare professionals which might affect their acceptance of the diagnosis and need for treatment. Where monogenic diabetes is misdiagnosed as type 1 diabetes, people will miss the opportunity to use oral therapies in place of insulin.”  

The consensus authors recommend adults with suspected T1D should be tested for islet antibodies. If the patient tests positive, they should be considered as having T1D. If they test negative, and are greater than aged 35 years, they should be assessed for features of monogenic diabetes or T2D. If they have features of monogenic diabetes 3 and C-peptide levels of  >200 pmol/L they should undergo genetic testing for monogenic diabetes.1   If they have C-peptide levels of <200 pmol/L or are without features of T2D, they likely have T1D.1

According to the consensus report, adults aged greater than 35 years should first be given a trial of non-insulin therapies if T1D is suspected.4,5  If there is uncertainty about the type of diabetes 3 years following a diagnosis, patients should have a C-peptide test.1  Patients with low (<200 pmol/L) levels are likely to have T1D. Those with high (>600 pmol/L) levels likely have T2D. Those with intermediate (200-600 pmol/L)levels may require additional C-peptide testing 5 years after diagnosis.

To manage T1D, the report stressed effective care including the use of exogenous insulin to maintain glucose levels. Patients should al receive care to reduce cardiovascular risk factors and minimize the psychosocial burden of living with a chronic condition.7-12

Physicians should be aware of Diabetes Management, Education, and Support (DSMES) which is an essential component of successful T1D care, according to the report, with the goal of equipping patients and their support systems with the knowledge, skills, and confidence to manage T1D  on a daily basis.13  For each patient, individual DSMES analysis should consider medical history, functional literacy, support systems, religious and cultural beliefs, health attitudes, physical limitations, socioeconomic status, and potential barriers.14  These components, according to the report, become especially important at the time of T1D diagnosis, when patients  have not met glycemic goals, when complications emerge, and during life transitions.15   Between 20% and 40% of people with T1D experience emotional distress at some point, such as feeling powerless and overwhelmed by the daily self-care demands of the disease. Depressed mood and elevated glycated hemoglobin (HbA1c) levels have also been found to be linked to the disorder.16

Glycemic targets for most adults with T1D, according to the consensus report, are:17:

  • Glycated hemoglobin (HbA1C):  <7%
  • Glucose management indicator:  <7%
  • Preprandial glucose:  4.4-7.2 mmol/L
  • 1–2-hour postprandial glucose:  <10.0 mmol/L
  • Time in range:  >70%  
  • Time below range:
    • Readings and time <3.9 mmol/L (<70 mg/dL; level 1 and level 2    hypoglycemia): <4% 
    • Readings and time <3.0 mmol/L (<54 mg/dL; level 2 hypoglycemia): <1%
  • Time above range:
    • Readings and time >10.0 mmol/L (180 mg/dL; level 1 and level 2 hyperglycemia):  <25%
    • Readings and time >13.9 mmol/L (>250 mg/dL; level 2 hyperglcemia): <5%
  • Glycemic variability:  £36%

Since it has become commercially available in 2006, the standard method for assessing glucose for most adults with T1D is continuous glucose monitoring (CGM). These devices have been found to be effective at improving HbA1C and reducing hypoglycemic events among patients who use insulin pumps or multiple daily injections (MDI).10, 11, 12, 18

“We have seen huge advances in insulin therapy and the means of delivery together with glucose monitoring devices. The best glucose levels are achieved with hybrid closed loop systems, and it is very exciting to see how close we are to fully closed loop systems,” said Dr Holt. ”In the century since the discovery of insulin, we can look back and see how far we have travelled since [Frederick Banting and Charles Best] discovered insulin. The rate of advancement is moving ever more rapidly and, if clinicians are to provide the best care for their patients with T1D, they need to be aware of the latest advances. For example, some of the new immunotherapy trials give promise that one day T1D will be preventable.”  

Dr Holt concludes: “I would urge people to read the [consensus] statement in its entirety, but for me, the highlights are the diagnostic algorithm for the diagnosis of T1D, the emphasis on the importance of psychosocial care and education, the recommendation that continuous glucose monitoring is the standard of care for T1D, and the discussion about insulin and its delivery.”

The Consensus Report was simultaneously published in the following medical journals:

Holt RIG, DeVries JH, Hess-Fischl A, et al. The management of type 1 diabetes in adults. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD). Diabetologia. 2021;1-44. doi:10.1007/s00125-021-05568-3

Holt, RIG, DeVries, JH, Hess-Fiscchl A, et al. The management of type 1 diabetes in adults. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes. Diabetes Care. 2021;44(11):2589-2625. doi:10.2337/dci21-0043

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original references and report for a full list of disclosures.


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