Academy of Diagnostics & Laboratory Medicine - Practice Guideline
Publication Date: 2023
Diabetes mellitus is a group of metabolic disorders of carbohydrate metabolism in which glucose is both underutilized and overproduced, resulting in hyperglycemia. The disease is classified conventionally into several clinical categories. Type 1 diabetes mellitus is usually caused by autoimmune destruction of the pancreatic islet β-cells, rendering the pancreas unable to synthesize and secrete insulin (1). Type 2 diabetes mellitus results from a combination of insulin resistance and inadequate insulin secretion (2, 3). Gestational diabetes mellitus (GDM) develops during approximately 17% of pregnancies, usually remits after delivery, and is a major risk factor for the development of type 2 diabetes later in life. Type 2 is the most common form of diabetes, accounting for 85% to 95% of diabetes in developed countries.
Diabetes is a common disease. Worldwide prevalence in 2021 was estimated to be approximately 537 million (10.5% of the global population) and is forecast to reach 783 million by 2045 (4). Based on 2017-2020 National Health and Nutrition Examination Survey data and 2018-2019 National Health Interview Survey data, the US Centers for Disease Control and Prevention estimated that there were 37.3 million people (11.3% of the US population) with diabetes (5). The number of adults with diabetes has also increased in other parts of the world. For example, China and India were thought to have 140.9 and 74.2 million adults with diabetes in 2021 and are expected to have 174.4 and 124.9 million, respectively, by 2045 (4). Approximately 45% of people with diabetes worldwide are thought to be undiagnosed (4).
The cost of diabetes in the US in 2012 was approximately $245 billion and increased to $327 billion by 2017 (6). The mean annual per capita healthcare costs for an individual with diabetes are approximately 2.3-fold higher than those for individuals who do not have diabetes (7). Worldwide spending in 2021 was thought to be $966 billion. The high costs of diabetes are attributable primarily to the chronic debilitating microvascular and macrovascular complications (6), which make diabetes the fourth most common cause of death in the developed world (8). About 6.7 million adults worldwide were thought to have died from diabetes-related causes in 2021 (4).
The Association for Diagnostics & Laboratory Medicine (ADLM, formerly AACC) and the American Diabetes Association issued “Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus” in 2002 (9, 10) and 2011 (11, 12). Here we review and update these recommendations using an evidence-based approach, especially in those areas where new evidence has emerged since the 2011 publications (13). The guideline committee, whose membership was predominantly from the US, included clinical, laboratory, and evidence-based guideline methodology experts. Members of the guideline committee have disclosed any financial, personal, or professional relationships that may constitute conflicts of interest with this guideline and received no direct funding related to the development of the recommendations. The perspectives and views of various international and national organizations, as well as other potential stakeholders (e.g., healthcare providers, people with diabetes, policymakers, regulatory bodies, health insurance companies, researchers, and industry), were taken into account during the public consultation process. The system developed in 2011 to grade both the overall quality of the evidence (Table 1) and the strength of recommendations (Table 2) was used, and the key steps and evidence summaries are detailed in the guideline and in the Data Supplement that accompanies the online version of this report (13). The literature was reviewed to the end of 2021.
This guideline focuses on the practical aspects of care in order to assist with decisions regarding the use or interpretation of laboratory tests while screening, diagnosing, or monitoring patients with diabetes. It covers the rationale, preanalytical, analytical, post-analytical, and, where applicable, emerging considerations, which alert the reader to ongoing studies and potential future aspects relevant to each analyte. The recommendations intend to supplement the American Diabetes Association guidelines and thus do not address any issues related to the clinical management of patients. The full version of this guideline and its accompanying supplements are available as a Special Report (13). Key recommendations are summarized.
These recommendations primarily target laboratory professionals, general practitioners, physicians, nurses, and other healthcare practitioners involved in the care of people with diabetes. The guidelines can be used by individuals with diabetes (where relevant, e.g., self–monitoring of blood glucose), policymakers, and payers for healthcare, as well as by researchers and manufacturers. Although recommendations were developed for national and international use and are intended to be generic, certain recommendations may not reflect views that are universally held or may have limited applicability in healthcare settings with differing organizational, cultural, and economic backgrounds. The guideline committee therefore advises users to adapt recommendations to local settings.