Dr. Ron’s Research Review – February 27, 2019

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This week’s research review focuses on non-fasting glucose

Clinicians frequently order random blood glucose (RBG) in routine laboratory panels. Although RBG values ≥200 mg/dL with hyperglycemic symptoms are diagnostic of diabetes, interpreting RBG results below this threshold is challenging, because the impact of food and calorie-containing drinks on glucose in non-fasting individuals is unclear. As a result, clinicians often ignore RBG values, even though they are strongly associated with undiagnosed diabetes and pre-diabetes and can identify those at risk of dysglycemia.
To improve interpretation of RBG values in non-fasting individuals without self-reported dysglycemia, we stratified participants in the National Health and Nutrition Examination Survey (NHANES) by hemoglobin A1C (HbA1c) and characterized the relationship between RBG and time since last caloric intake. (Bowen et al., 2018)
In the first 8 h after caloric intake, those with undiagnosed dysglycemia had significantly higher RBG values than those with normoglycemia. Within 4 h of caloric intake, those with undiagnosed dysglycemia had RGB values that were ≥100 mg/dL and were 14–18 mg/dL higher than those with normoglycemia (Fig. 1). Those with normoglycemia had RBG values <100 mg/dL at all time points. By 6 h, even those with undiagnosed dysglycemia had RBG values <100 mg/dL.
Rather than ignore RBG values ≥100 mg/dL measured within 4 h of eating or drinking, clinicians should order gold-standard diabetes tests to improve detection of undiagnosed dysglycemia.
Asymptomatic RBG values ≥100 mg/dL are a strong indicator of diabetes risk and are associated with undiagnosed dysglycemia. Ordering gold-standard diabetes tests on patients with unknown glycemic status and RBG values ≥100 mg/ dL - regardless of the type or time of last caloric intake - may simplify RBG interpretation and improve detection of dysglycemia.

An earlier paper recommends cutoffs of 100–110 mg/dl for diabetes and 95–100 mg/dl for any glucose intolerance. (Ziemer et al., 2008)

 

Dr. Ron

 


Articles

 

Doc, I Just Ate: Interpreting Random Blood Glucose Values in Patients with Unknown Glycemic Status.
            (Bowen et al., 2018)  Download
Clinicians frequently order random blood glucose (RBG) in routine laboratory panels. Although RBG values ≥200 mg/dL with hyperglycemic symptoms are diagnostic of diabetes, interpreting RBG results below this threshold is challenging, because the impact of food and calorie-containing drinks on glucose in non-fasting individuals is unclear. As a result, clinicians often ignore RBG values1—even though they are strongly associated with undiagnosed diabetes and prediabetes and can identify those at risk of dysglycemia.2, 3 To improve interpretation of RBG values in non-fasting individuals with- out self-reported dysglycemia, we stratified participants in the National Health and Nutrition Examination Survey (NHANES) by hemoglobin A1C (HbA1c) and characterized the relationship between RBG and time since last caloric intake.

Performance of a Random Glucose Case-Finding Strategy to Detect Undiagnosed Diabetes.
            (Bowen et al., 2017) Download
INTRODUCTION:  Random glucose <200 mg/dL is associated with undiagnosed diabetes but not included in screening guidelines. This study describes a case-finding approach using non-diagnostic random glucose values to identify individuals in need of diabetes testing and compares its performance to current screening guidelines. METHODS:  In 2015, cross-sectional data from non-fasting adults without diagnosed diabetes or prediabetes (N=7,161) in the 2007-2012 National Health and Nutrition Examination Surveys were analyzed. Random glucose and survey data were used to assemble the random glucose, American Diabetes Association (ADA), and U.S. Preventive Services Task Force (USPSTF) screening strategies and predict diabetes using hemoglobin A1c criteria. RESULTS:  Using random glucose ≥100 mg/dL to select individuals for diabetes testing was 81.6% (95% CI=74.9%, 88.4%) sensitive, 78% (95% CI=76.6%, 79.5%) specific and had an area under the receiver operating curve (AROC) of 0.80 (95% CI=0.78, 0.83) to detect undiagnosed diabetes. Overall performance of ADA (AROC=0.59, 95% CI=0.58, 0.60), 2008 USPSTF (AROC=0.62, 95% CI=0.59, 0.65), and 2015 USPSTF (AROC=0.64, 95% CI=0.61, 0.67) guidelines was similar. The random glucose strategy correctly identified one case of undiagnosed diabetes for every 14 people screened, which was more efficient than ADA (number needed to screen, 35), 2008 USPSTF (44), and 2015 USPSTF (32) guidelines. CONCLUSIONS:  Using random glucose ≥100 mg/dL to identify individuals in need of diabetes screening is highly sensitive and specific, performing better than current screening guidelines. Case-finding strategies informed by random glucose data may improve diabetes detection. Further evaluation of this strategy's effectiveness in real-world clinical practice is needed.

Random plasma glucose in serendipitous screening for glucose intolerance: screening for impaired glucose tolerance study 2.
            (Ziemer et al., 2008) Download
BACKGROUND:  With positive results from diabetes prevention studies, there is interest in convenient ways to incorporate screening for glucose intolerance into routine care and to limit the need for fasting diagnostic tests. OBJECTIVE:  The aim of this study is to determine whether random plasma glucose (RPG) could be used to screen for glucose intolerance. DESIGN:  This is a cross-sectional study. PARTICIPANTS:  The participants of this study include a voluntary sample of 990 adults not known to have diabetes. MEASUREMENTS:  RPG was measured, and each subject had a 75-g oral glucose tolerance test several weeks later. Glucose intolerance targets included diabetes, impaired glucose tolerance (IGT), and impaired fasting glucose(110) (IFG(110); fasting glucose, 110-125 mg/dl, and 2 h glucose < 140 mg/dl). Screening performance was measured by area under receiver operating characteristic curves (AROC). RESULTS:  Mean age was 48 years, and body mass index (BMI) was 30.4 kg/m(2); 66% were women, and 52% were black; 5.1% had previously unrecognized diabetes, and 24.0% had any "high-risk" glucose intolerance (diabetes or IGT or IFG(110)). The AROC was 0.80 (95% CI 0.74-0.86) for RPG to identify diabetes and 0.72 (0.68-0.75) to identify any glucose intolerance, both highly significant (p < 0.001). Screening performance was generally consistent at different times of the day, regardless of meal status, and across a range of risk factors such as age, BMI, high density lipoprotein cholesterol, triglycerides, and blood pressure. CONCLUSIONS:  RPG values should be considered by health care providers to be an opportunistic initial screening test and used to prompt further evaluation of patients at risk of glucose intolerance. Such "serendipitous screening" could help to identify unrecognized diabetes and prediabetes.

References

Bowen, ME, et al. (2017), ‘Performance of a Random Glucose Case-Finding Strategy to Detect Undiagnosed Diabetes.’, Am J Prev Med, 52 (6), 710-16. PubMed: 28279547
——— (2018), ‘Doc, I Just Ate: Interpreting Random Blood Glucose Values in Patients with Unknown Glycemic Status.’, J Gen Intern Med, 33 (2), 142-44. PubMed: 29134572
Ziemer, DC, et al. (2008), ‘Random plasma glucose in serendipitous screening for glucose intolerance: screening for impaired glucose tolerance study 2.’, J Gen Intern Med, 23 (5), 528-35. PubMed: 18335280