February 2024
Laboratory testing in diagnosing and managing diabetes

New guidelines from the American Diabetes Association

Sponsoring organisation: American Diabetes Association. 

Background: In recent years, management of diabetes has undergone several changes, including increased use of continuous glucose monitoring and availability of novel treatments for patients with type 2 diabetes and diabetic nephropathy. New guidelines from the American Diabetes Association discuss the role of laboratory testing in the current era of diabetes management.

Key points: Although much of this guideline is geared toward specialists and laboratory directors, recommendations relevant to adult general practice include the following:

  • all insulin-treated patients with type 1 or type 2 diabetes should use blood glucose monitoring or continuous glucose monitoring to help determine insulin doses, detect hypoglycaemia and achieve better glycaemic control. However, the authors strongly recommend against use of blood glucose monitoring in noninsulin-treated patients, in whom BGM does not facilitate additional glycated haemoglobin (HbA1c) reduction
  • continuous glucose monitoring is recommended for patients with type 1 diabetes who are not meeting glycaemic targets or have hypoglycaemia or hypoglycaemia unawareness. Although continuous glucose monitoring can be considered in insulin-treated patients with type 2 diabetes, the literature is less robust, showing HbA1c improvements but no hypoglycaemia reduction
  • measuring islet autoantibodies, C-peptide levels or both can help distinguish between type 1 and type 2 diabetes when a patient’s presentation (e.g. ketoacidosis) makes classification uncertain. Of note, recent evidence suggests that adult-onset type 1 diabetes is not rare (NEJM JW Gen Med Oct 15 2023 and Ann Intern Med 2023; 176: 1567-1568). However, in most patients, routine testing of islet autoantibodies, insulin, pro-insulin and C-peptide levels is not recommended
  • urine albumin-to-creatinine ratio (uACR) should be measured annually in all adults with diabetes and every six months in those with abnormal uACR or low glomerular filtration rates. Due to large within-individual variation in albumin excretion, the authors recommend checking uACR in a first morning void urine sample (ideally) or routinely at the same time of day and at least two hours after eating. Emphasis on these measurements is based on increasing use of sodium-glucose cotransporter-2 (SGLT-2) inhibitors and aldosterone antagonists (and not simply renin-angiotensin antagonists) in patients with early evidence of nephropathy.

Comment: These guidelines offer several straightforward recommendations for evidence-based clinical practice. For example, clinicians can promote use of continuous glucose monitoring in insulin-treated patients (particularly with type 1 diabetes) with hyper- or hypoglycaemia and can avoid blood glucose monitoring in noninsulin-treated patients. Other recommendations, such as checking uACR in the first morning void, are more challenging to implement.

Molly S. Brett, MD, Assistant Professor of Medicine, University of Colorado, Boulder, USA.

Sacks DB, et al. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Diabetes Care 2023 Oct 1; 46: e151-e199.

This summary is taken from the following Journal Watch titles: General Medicine, Ambulatory Medicine, Hospital Medicine.

Diabetes Care