The glucose management indicator (GMI)—an estimated measure of hemoglobin A1c (HbA1c) recommended when managing diabetes with continuous glucose monitoring (CGM)—may be an unreliable measure of type 2 diabetes glycemic control and should be interpreted cautiously, new research says (Clin Chem 2023; doi: 10.1093/clinchem/hvac210).
HbA1c has its own limitations: It does not characterize variability or acute spikes in glucose, and it may be less reliable with altered red cell turnover and certain comorbidities, such as some types of anemia or chronic kidney disease. GMI is derived primarily in young adults with type 1 diabetes, so GMI’s performance in patients with type 2 diabetes is poorly characterized. Yet clinicians increasingly rely on it for these patients.
In response, the researchers prospectively studied 144 adults with a mean age of 59.4 years with obstructive sleep apnea and type 2 diabetes who did not use insulin. After measuring HbA1c at the study screening visit, participants simultaneously wore two CGM sensors (Dexcom G4 and Abbott Libre Pro) for up to 4 weeks—2 weeks at baseline and 2 weeks at the 3-month follow-up visit. The researchers calculated GMI using CGM data from each sensor.
The mean difference between HbA1c and GMI was just 0.12–0.14 percentage points, or approximately 2 mmol/mol. However, the two measures were only moderately correlated (r = 0.68–0.71), and researchers found substantial variability in GMI across measurements of HbA1c (root mean squared error: 0.66–0.69 percentage points [7 to 8 mmol/mol]). Between 36% and 43% of participants had a clinically significant, absolute difference between HbA1c and GMI of 0.5 percentage points or more, and 9% to 18% had an absolute difference greater than 1 percentage point. Discordance was higher in the Libre Pro than the Dexcom G4.
LC–MS/MS ASSAY SHOWS PROMISE FOR ANTIDEPRESSANT TESTING
A new automated liquid chromatography tandem mass spectrometry (LC-MS/MS) assay can simultaneously quantify four different classes of antidepressants commonly prescribed to women, according to recent findings (Sci Rep 2023; doi: 10.1038/s41598-023-29229-0).
While the percentage of patients using prescribed antidepressants has skyrocketed, finding suitable treatments remains a long trial-and-error process to deal with side-effects and determine overall treatment efficacy. The challenge increases for women who become pregnant. In response, studies have focused on effective methods to quantify and monitor a wide range of antidepressants that clinicians prescribe specifically to women.
In the current study, researchers validated an automated triple quad LC–MS/MS‐based assay for simultaneous quantification of the antidepressants, developed a prototype kit using a small sample volume with minimal sample preparation, and compared the assay to previously reported studies in terms of precision and accuracy. The researchers focused on the simultaneous detection of the norepinephrine-dopamine reuptake inhibitor (NDRI) bupropion; selective serotonin reuptake inhibitors (SSRIs) citalopram, olanzapine, sertraline, and vilazodone; the tricyclic inhibitors (TCIs) desipramine and imipramine; and the serotonin and norepinephrine reuptake inhibitor (SNRI) milnacipran.
Using a small 20 μL serum sample, the researchers measured the drugs across a range of 1.0 to 230 ng/mL. The method exhibited a linearity of R2 greater than or equal to 0.99 when detected in multiple reaction monitoring mode (MRM) and percent coefficient of variation (CV) of less than or equal to 20% for all analytes across the board. When compared with existing commercial kits available outside of the United States, the prototype kit proved easily automated with minimal sample loss.
They said that their prototype has potential as an automated method for quantifying antidepressants in postpartum mothers and infants, determining how much of the drugs may be passed on during the nursing period, and monitoring postpartum depression.
INSULIN PUMPS EFFECTIVE IN YOUTHS WITH TYPE 1 DIABETES
Even as the data from continuous glucose monitoring (CGM) has come under scrutiny, new research shows that using insulin pumps with real-time CGM is associated with more frequent meeting of clinical and time-in-range targets and lower probability of severe adverse events compared with other treatment modalities (JAMA Netw Open 2023; doi: 10.1001/jamanetworkopen. 2023.0077).
In adults with type 1 diabetes, use of real-time CGM, compared with intermittently scanned CGM, has been associated with improved glycemic control and outcomes.
Researchers aimed to assess real-world data on how CGM affected time-in-range clinical targets among youth with type 1 diabetes. Their multinational cohort study included 5,219 children, adolescents, and young adults under age 21 with type 1 diabetes for at least 6 months. Participants, who provided CGM data, were divided into four treatment modalities: intermittently scanned CGM with or without insulin pump use, and real-time CGM with or without insulin pump use.
Participants’ median HbA1c level was 7.4%. Treatment modality was associated with the proportion of individuals achieving recommended clinical targets. Users of real-time CGM concurrently with an insulin pump were most likely to achieve targets for more than 70% time-in-range, less than 25% above, and less than 4% time below clinical target ranges. CGM and pump users had the adjusted highest time in range and were the least likely to experience severe hypoglycemia and diabetic ketoacidosis events.
The proportion of participants achieving the recommended more than 70% time-in-range target was 36.2% for real-time CGM plus insulin pump use (95% CI, 33.9%–38.4%), 20.9% for real-time CGM plus injection use (95% CI, 18.0%–24.1%), 12.5% for intermittently scanned CGM plus injection use (95% CI, 10.7%–14.4%), and 11.3% for intermittently scanned CGM plus insulin pump use (95% CI, 9.2%–13.8%).
The proportion of participants who were 25% of time above target range included 32.5% of those using real-time CGM plus insulin pump (95% CI, 30.4%–34.7%) and 12.8% of those in the intermittently scanned CGM plus insulin pump groups (95% CI, 10.6%–15.4%). Proportion of participants who were less than 4% time below range target included 73.1% of the real-time CGM plus insulin pump group (95% CI, 71.1%–75.0%) and 47.6% of the intermittently scanned CGM plus insulin pump group, (95% CI, 44.1%–51.1%). Adjusted time in range was highest among real-time CGM plus insulin pump users at 64.7% (95% CI, 62.6%–66.7%).
The findings suggest that concurrent real-time CGM and insulin pump use should be more readily available to youths with type 1 diabetes, the researchers said.