Glucose Intolerance Guidelines

Updated: Jul 08, 2020
  • Author: Samuel T Olatunbosun, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Guidelines Summary

ADA Screening Guidelines

Type 1 diabetes

The 2019 American Diabetes Association (ADA) guidelines notes that screening with an autoantibodies panel for type 1 diabetes risk is currently recommended only in the setting of a research trial or in first-degree relatives of a proband with type 1 diabetes. [4]

Type 2 diabetes

Equally appropriate tests for prediabetes and type 2 diabetes are fasting plasma glucose (FPG), 2-hour plasma glucose (PG) during a 75-g oral glucose tolerance test (GTT), and HBA1C. [4]

Consider risk-based screening for prediabetes and/or type 2 diabetes after the onset of puberty or after age 10 years (whichever occurs earlier) in overweight or obese children and adolescents (body mass index [BMI] ≥85th percentile or ≥95th percentile, respectively) and those with additional risk factors for diabetes. [4]

In asymptomatic adults, consider screening tests for prediabetes and type 2 diabetes mellitus with an informal assessment of risk factors or validate tools. [4] Consider screening tests for prediabetes and/or type 2 diabetes in asymptomatic adults of any age who are overweight or obese (BMI ≥25 kg/m2 (≥23 kg/m2 for Asian Americans) and have one or more additional risk factors, [4] including the following [1] :

  • Physical inactivity

  • First-degree relative with diabetes

  • High-risk ethnic background (eg, African American, Latino, Native American, Asian American, Pacific Islander)

  • Women who were diagnosed with gestational diabetes mellitus

  • Hypertension of 140/90 mm Hg and greater or on therapy for hypertension

  • High-density lipoprotein cholesterol (HDL-C) level below 35 mg/dL (0.90 mmol/L) and/or triglyceride level above 250 mg/dL (2.82 mmol/L)

  • Women with polycystic ovarian syndrome (PCOS) [69, 70, 71]

  • HBA1C ≥5.7% [39 mmol/mol], impaired glucose tolerance (IGT), or impaired fasting glucose (IFG) on previous testing

  • Other clinical conditions associated with insulin resistance (eg, severe obesityacanthosis nigricans)

  • History of cardiovascular disease

All individuals should be tested beginning at age 45 years. [4]  If test results are normal, it is reasonable to repeat testing at a minimum of 3-year intervals. Consider more testing more frequently depending on the initial results and risk status.

Test annually patients with prediabetes (HBAIC ≥5.7% [39 mmol/mol], IGT, or IFG). Women previously diagnosed with gestational diabetes should have lifelong testing at a minimum of every 3 years. [4]


Novel CV Risk Reduction Therapies in T2D and CVD

The American College of Cardiology released expert consensus decision pathways on the use of two major new classes of diabetes drugs—sodium-glucose cotransporter type 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1RAs)—for cardiovascular (CV) risk reduction in patients with type 2 diabetes (TD2) and atherosclerotic CV disease (ASCVD) in November 2018. [72, 73] The main focus of management is in the outpatient ambulatory setting.

The SGLT2 inhibitors appear to reduce major adverse CV events (MACE) and the risk of heart failure (HF) but increase the risk for genital mycotic infections, whereas GLP-1RAs offer reductions in MACE but are associated with transient nausea and vomiting. Both classes of agents have benefits in reducing blood pressure and weight, and they have a low risk for hypoglycemia.

For CV risk reduction, initiate agents with demonstrated CV benefit from either drug class at the lowest doses; no uptitration is necessary for SGLT2 inhibitors, whereas the GLP-1RAs should be slowly uptitrated (to avoid nausea) to the maximal tolerated dose.

At the initiation of an SGLT2 inhibitor or a GLP-1RA agent, clinicians should avoid hypoglycemia in patients by monitoring those with A1C levels near or below target, particularly when patients' existing diabetes therapies include sulfonylureas, glinides, or insulin.

In addition to reducing MACE and CV death, SGLT2 inhibitors are also suitable for preventing hospitalization for HF.

Empagliflozin is the preferred SGLT2 inhibitor based on the available evidence and overall benefit-risk balance.

Liraglutide should be the preferred agent among the GLP-1RAs for CV event risk reduction.

Two SGLT2 inhibitors (ie, canagliflozin, ertugliflozin) appear to be associated with an increased risk of amputation. It is unclear whether or not this is a class effect; therefore, clinicians should closely monitor patients on these agents who have a history of amputation, peripheral arterial disease, neuropathy, or diabetic foot ulcers.

Patients with T2D and clinical ASCVD on metformin therapy (or in whom metformin is contraindicated or not tolerated) should have an SGLT2 inhibitor or GLP-1RA with proven CV benefit added to their treatment regimen. For patients not on background metformin therapy, practitioners may use their clinical judgment to prescribe an SGLT2 inhibitor or GLP-1RA for CV risk reduction.

It appears reasonable to concomitantly use an SGLT2 inhibitor and a GLP-1RA with demonstrated CV benefit if clinically indicated, although such combination therapy has not been studied for CVD risk reduction.