A new consensus statement from a range of diabetes organizations aims to standardize definitions for clinically meaningful outcome measures beyond hemoglobin A1c (HbA1c) for individuals with type 1 diabetes.
They plan to include hypoglycemia and time in range — outcomes that are now much easier to document given the increasing use of continuous glucose monitoring (CGM) among patients with diabetes.
The statement is a joint effort by the American Association of Clinical Endocrinologists, American Association of Diabetes Educators, American Diabetes Association (ADA), Endocrine Society, JDRF International, Leona M and Harry B Helmsley Charitable Trust, Pediatric Endocrine Society, and T1D Exchange.
It was published online November 21, 2017 in Diabetes Care by a steering committee comprised of members of all the organizations and led by Gina Agiostratidou, PhD, a program director at the Helmsley Trust.
HbA1c does not capture short-term variations in blood glucose, exposure to hypoglycemia and hyperglycemia, or the impact of blood glucose variation on quality of life, they say.
So the committee has developed new standardized definitions for hypoglycemia, hyperglycemia, time in range, and diabetic ketoacidosis (DKA) in type 1 diabetes, with the immediate goal being their use as primary and secondary end points in research aimed at the development and evaluation of new therapies and technologies.
“It is not our expectation for any of the outcomes defined in this document to replace HbA1c, as it remains an important outcome measure, but rather that they supplement its utility and allow for the capture of a more comprehensive understanding of how interventions might influence people with diabetes,” write Dr Agiostratidou and colleagues.
CGM: A Turning Point in Diabetes Management
Also published in the December issue of Diabetes Care are several other articles devoted to new clinical issues in type 1 and type 2 diabetes that have arisen with the advent of CGM.
“Periodically, a new idea, method, or tool leads to a turning point in the management of diabetes. We believe such a moment is now upon us, brought by development of reliable devices for CGM,” diabetes thought leaders Matthew C Riddle, MD, Oregon Health & Science University, Portland, Oregon, Hertzel C Gerstein, MD, McMaster University, Hamilton, Ontario, Canada, and William T Cefalu, MD, of the ADA, Arlington, VA, write in an editorial.
The three endocrinologists add: “Obtaining profiles of glucose levels continuously, day and night, is likely to bring new scientific insights and greater ability to individualize treatments for patients with both type 1 diabetes and type 2 diabetes.”
New Definitions for Hypo- and Hyperglycemia, Time in Range, and DKA
The panel based the new type 1 diabetes definitions on published evidence — including from people with type 2 diabetes and without diabetes — as well as clinical experience and expertise of the steering committee and advisory committees.
Hypoglycemia is divided into three levels: blood glucose 54–70 mg/dL (3.0–3.9 mmol/L), blood glucose < 54 mg/dL (< 3.0 mmol/L), and severe events characterized by altered mental and/or physical status requiring assistance.
Hyperglycemia is divided into two levels: elevated blood glucose (180–250 mg/dL [10–13.9 mmol/L]) and very elevated (> 250mg/dL [> 13.9 mmol/L]).
Time in range is defined as percentage of blood glucose readings within 70–180 mg/dL (3.9–10.0 mmol/L) per unit of time, a relatively new outcome measure derived from CGM data.
And DKA is defined as elevated serum or urine ketones (greater than the upper limit of normal) and serum bicarbonate < 15 mmol/L or blood pH < 7.3.
The new standardized hypoglycemia definition in particular, which is also provided in another of the new Diabetes Care articles, could apply to research involving both types of diabetes, the editorialists point out.
Consensus on the classification will simplify comparison of the effects of glucose-lowering therapies across different drugs and a range of patient characteristics, they note.
“Standardized data collection and reporting may then open the door to a paradigm shift in regulatory assessment of therapies to include hypoglycemia as a relevant and reliable consideration.”
CGM Is a Unique But Complex Tool Requiring Support and Instruction
Two articles pertain specifically to CGM use. One article, an international consensus on the use of CGM, summarizes a February 2017 meeting of the Advanced Technologies & Treatments for Diabetes congress attended by CGM experts.
It discusses in detail and makes recommendations on the use of HbA1c as a measure of glycemic control, the use of both fingerstick and CGM to guide management and asses outcomes in different patient populations, minimum requirements for CGM performance, definition and assessment of hypoglycemia in clinical studies (including the same definition as in the type 1 diabetes article), assessment of glycemic variability and time in range, and visualization, analysis, and documentation of key CGM metrics.
The other CGM-related article on recommendations for improving the clinical value and use of CGM by the European Association for the Study of Diabetes and ADA Diabetes Technology working group was originally published online October 25, 2017.
Drs Riddle, Gerstein, and Cefalu write: “Fortunately, because CGM can be both a clinical guide and a unique tool for clinical investigation, research questions that were previously out of reach can now be studied.”
One example they cite is the use of the technology to investigate the differences between Caucasians and African-Americans in the relationship of HbA1c to mean glucose.
Important future uses, they add, will be to capture glycemic variability and previously missed hypoglycemic episodes to assess the role of those factors in outcomes such as cardiovascular events.
And of course, “CGM has several potential clinical uses. Its use to ‘close the loop’ by linking ongoing glycemic trends directly to insulin delivery systems is a leading goal.”
However, the trio also urge caution because of the complexity and cost of the technology.
“Instruction, advice, and support provided by a physician or other provider experienced in intensive diabetes management remains essential when applying CGM data to individualize and enhance therapeutic tactics. Because optimal use of CGM may require more rather than less advice and support, cost-effective use of CGM will require defining specific groups of patients who benefit the most.”
Importantly, “the experience of patients using CGM must remain a central concern, with ways to improve education and satisfaction explored to obtain the greatest return on this investment of time and resources.”
Dr Agiostratidou reported no relevant financial relationships. Disclosures for Dr Riddle, Dr Gerstein and Dr Cefalu are available online.
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