Introduction

The prevalence of diabetes has reached alarming proportions worldwide; the number of adults living with diabetes is predicted to rise to 643 million by 2030 [1]. The dynamic nature of this chronic condition, coupled with its multifaceted impact on health, necessitates regular revisions to guidelines in diabetes care. The American Diabetes Association (ADA) has played a crucial role in guiding diabetes care by serving as a leading authority in the field of diabetes research, education, advocacy, and development of standards of care. Since 1989 the ADA has provided an annual guidance document on Standards of Medical Care in Diabetes. This commentary aims to distill the updates and recommendations from the latest ADA 2024 standards of care specifically pertaining to laboratory assessments in diabetes management.

Diagnosis and confirmatory testing

Traditionally, the classification and diagnosis of diabetes primarily depended on plasma glucose levels and symptom presentation until the ADA endorsement of glycated hemoglobin (HbA1c) in 2010. HbA1c is a reliable retrospective marker of blood glucose control over the past 6–8 weeks [2]. HbA1c testing offers several advantages over traditional glucose tests, including greater convenience, stability, and less susceptibility to day-to-day variations. Despite its higher cost and limited access in certain regions, HbA1c provides a weighted average of blood glucose levels, offering a more reflective measure of recent glycemic control. Over time, HbA1c has evolved as a pivotal tool in both the diagnosis and management of diabetes. In contrast to the ADA 2023 guidelines, which prioritized fasting plasma glucose, the latest ADA 2024 guidelines affirm the pivotal role of HbA1c for diabetes diagnosis and screening and place HbA1c testing at the forefront of the diagnostic hierarchy for both diabetes and prediabetes. Recommendations for the diagnostic threshold remain unchanged—≥ 6.5% for HbA1c, using a National Glycohemoglobin Standardization Program (NGSP)-certified method that’s traceable to the Diabetes Control and Complications Trial (DCCT) [3].

For diabetes screening and diagnosis using point-of-care testing (POCT) HbA1c devices, the ADA emphasizes several factors. The POCT assays should be approved by the U.S. Food and Drug Administration (FDA) or NGSP-certified and can be conducted in laboratories or sites meeting Clinical Laboratory Improvement Amendments (CLIA) certification and quality standards. These standards encompass specific personnel requirements, including documented annual competency assessments, and regular participation in approved proficiency testing programs three times per year. This ensures adherence to high-quality standards in HbA1c testing, promoting accurate and reliable results in diabetes management [3].

However, in the presence of hemoglobin variants, pregnancy, glucose-6-phosphate dehydrogenase deficiency, and other conditions that might potentially interfere with accurate HbA1c measurements, plasma glucose levels are preferred. Furthermore, in situations where elevated blood glucose levels might not be consistently apparent, the diagnosis of diabetes necessitates two abnormal test results (HbA1c and plasma glucose) either simultaneously or at different time points. In such scenarios, alternative biomarkers such as fructosamine and glycated albumin emerge as viable options for monitoring glycemic status. Fructosamine reflects the total pool of glycated serum proteins, mainly albumin, reflecting glycemic trends over a span of 2–4 weeks—a relatively shorter duration compared to A1C. Although these biomarkers show a strong correlation and are associated with long-term complications based on epidemiological evidence, the empirical support for their application is not as robust as that for HbA1c [4].

Personalized management

Associated comorbidities

Pregnancy

Concurrent with a notable rise in the prevalence of both type 1 and type 2 diabetes among individuals of childbearing age, there has been a significant surge in reported cases of gestational DM (GDM). GDM is defined as a glucose tolerance diagnosed for the first time during pregnancy and not aligning with either the type 1 or type 2 diabetes criteria [23]. Studies have reported significant associations between maternal plasma glucose elevations during pregnancy and adverse fetal outcomes [24]. Although the effectiveness of first-trimester screening for GDM is debated, preconception counselling has gained significance in achieving normal plasma glucose levels to prevent congenital anomalies in the fetus and mitigate maternal complications in those with diabetes [25]. It is noteworthy that pregnancy is associated with reduced HbA1c levels owing to increased red blood cell turnover; thus, the recommended HbA1c target in pregnancy is < 6%, although this goal can be adjusted to < 7% in cases where there is a risk of hypoglycemia [26]. Considering these alterations, it might be essential to monitor HbA1c levels more frequently, perhaps on a monthly basis during pregnancy. Furthermore, in addition to conventional pre- and postprandial glucose monitoring, continuous glucose monitoring (CGM) can help achieve glycemic targets in GDM, although its cost-effectiveness is controversial in patients with HbA1c levels < 6% [27]. Nonetheless, lifestyle modifications, including medical nutrition therapy form a crucial part of diabetes management in pregnancy.

Diabetes technology

One of the most important advances in diabetes technology is the introduction of CGM devices. These devices are equipped with sensors containing a glucose-oxidase platinum electrode to measure glucose concentrations in interstitial fluid [28]. Currently, three types of CGM devices are available: rtCGM (measure and display real-time glucose levels), isCGM (continuously measure glucose levels but require intermittent scanning for visualization), and professional CGM (used to monitor glycemic data in professional healthcare settings). Interestingly, the ADA has now provided clinicians and care-givers guidance on desirable goals for CGM metrics—time in range, time above range, and time below range. These parameters can be used for the assessment of glycemic status and evaluation of treatment plans. Moreover, guidance has been provided on the standardization of reports generated by CGM devices, incorporating visual cues like the ambulatory glucose profile. This would be particularly helpful to guide physical activity, nutritional therapy, and medication management. CGM devices can be beneficial in patients with type 1 or type 2 diabetes on insulin therapy but should be only offered after proper education regarding their use, safety and interfering factors [29]. Another area of rapidly evolving technologies is the integration of CGM data with insulin delivery systems and electronic health records. However, there remains substantial work to improve outcomes in diabetes management arising from these new technologies [30].

Discussion and conclusion

The evolving landscape of diabetes care necessitates continuous updates in guidelines to address the multifaceted nature of this chronic condition. The key revisions made to the ADA guidelines in 2024 are summarized in Table 1.

These guidelines utilize a rigorous level of evidence methodology, categorizing recommendations based on the strength of supporting evidence, ranging from high-quality randomized controlled trials to expert consensus or clinical experience. Accordingly, the recommendations are meticulously assigned ratings of A, B, or C, which directly correlate with the quality of evidence supporting each recommendation. Additionally, expert opinion is denoted by the category E. This systematic approach ensures that recommendations are grounded in the most current and reliable scientific evidence available, enhancing their credibility and applicability in clinical practice and laboratory settings. Table 2 provides a structured summary of the major recommendations and levels of evidence from the ADA 2024 guidelines.

In conclusion, the latest guidelines on Standards of Medical Care in Diabetes underscore the paramount importance of laboratory assessments in diabetes management, particularly focusing on the diagnostic role of HbA1c and its reliability in diagnosing and screening for diabetes, albeit with considerations for potential interferences. Precision medicine is highlighted, urging the categorization of patients into the correct specific diabetes subsets for personalized management. The guidelines also stress the complexities in distinguishing between diabetes types and acknowledge the emergence of hybrid forms, necessitating tailored treatment approaches. Emphasis is also placed on managing associated comorbidities such as CVD, diabetic kidney disease, and the intricate CKM syndrome, advocating comprehensive care models. Additionally, the role of CGM devices in achieving glycemic control is highlighted. However, despite technological advances, further research is warranted to improve outcomes in diabetes management. Through this article, laboratory personnel can glean the updates in the latest ADA guidelines on Standards of Medical Care in Diabetes.