Hypoglycemia in children and young adults with cystic fibrosis during oral glucose tolerance testing vs. continuous glucose monitoring.

BACKGROUND: Hypoglycemia is common in people with cystic fibrosis (pwCF) during oral glucose tolerance tests (OGTTs) and in the free-living setting, yet its pathophysiology remains unclear. OBJECTIVE: To evaluate hypoglycemia in children and young adults with CF by OGTT and continuous glucose monitoring (CGM). METHODS: A 3-h OGTT was performed in children and young adults with CF and healthy controls (HC). Individuals were classified as experiencing hypoglycemia on OGTT (glucose <70 mg/dL) or not. Insulin, C-peptide, glucose, glucagon, and incretins were measured. CGM was performed for 7 days in the free-living setting. Measures of insulin sensitivity, beta cell function accounting for insulin sensitivity, and insulin clearance were calculated. RESULTS: A total of 57 participants (40 CF and 17 HC) underwent assessment. Rates of hypoglycemia by OGTT were similar in pwCF (53%, 21/40) compared to HC (35%, 6/17), p = 0.23. PwCF compared to HC had higher A1c; on OGTT higher and later glucose peaks, later insulin peaks; and on CGM more glucose variability. CF Hypo+ versus CF Hypo- had higher lung function, higher insulin sensitivity, higher beta cell function accounting for insulin sensitivity, and decreased CGM variability. When comparing CF Hypo+ to HC Hypo+, although rates of hypoglycemia are similar, pwCF had blunted glucagon responses to hypoglycemia. OGTT hypoglycemia was not associated with CGM hypoglycemia in any group. CONCLUSION: Youth with CF have increased insulin sensitivity and impaired glucagon response to hypoglycemia on OGTT. Hypoglycemia on OGTT did not associate with free-living hypoglycemia.

Diabetes Care Barriers, Use, and Health Outcomes in Younger Adults With Type 1 and Type 2 Diabetes.

Importance: Treatment challenges exist for younger adults with type 1 (T1D) and type 2 diabetes (T2D). Health care coverage, access to, and use of diabetes care are not well delineated in these high-risk populations. Objective: To compare patterns of health care coverage, access to, and use of diabetes care and determine their associations with glycemia among younger adults with T1D and with T2D. Design, Setting, and Participants: This cohort study analyzed data from a survey that was jointly developed by 2 large, national cohort studies: the SEARCH for Diabetes in Youth (SEARCH) study, an observational study of individuals with youth-onset T1D or T2D, and the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study, a randomized clinical trial (2004-2011) followed by an observational study (2012-2020). The interviewer-directed survey was administered during in-person study visits in both studies between 2017 and 2019. Data analyses were performed between May 2021 and October 2022. Main Outcomes and Measures: Survey questions addressed health care coverage, usual sources of diabetes care, and frequency of care use. Glycated hemoglobin (HbA1c) levels were assayed in a central laboratory. Patterns of health care factors and HbA1c levels were compared by diabetes type. Results: The analysis included 1371 participants (mean [range] age, 25 [18-36] years; 824 females [60.1%]), of whom 661 had T1D and 250 had T2D from the SEARCH study and 460 had T2D from the TODAY study. Participants had a mean (SD) diabetes duration of 11.8 (2.8) years. More participants with T1D than T2D in both the SEARCH and TODAY studies reported health care coverage (94.7%, 81.6%, and 86.7%), access to diabetes care (94.7%, 78.1%, and 73.4%), and use of diabetes care (88.1%, 80.5%, and 73.6%). Not having health care coverage was associated with significantly higher mean (SE) HbA1c levels in participants with T1D in the SEARCH study (no coverage, 10.8% [0.5%]; public, 9.4% [0.2%]; private, 8.7% [0.1%]; P < .001) and participants with T2D from the TODAY study (no coverage, 9.9% [0.3%]; public, 8.7% [0.2%]; private, 8.7% [0.2%]; P = .004). Medicaid expansion vs without expansion was associated with more health care coverage (participants with T1D: 95.8% vs 90.2%; participants with T2D in SEARCH: 86.1% vs 73.9%; participants with T2D in TODAY: 93.6% vs 74.2%) and lower HbA1c levels (participants with T1D: 9.2% vs 9.7%; participants with T2D in SEARCH: 8.4% vs 9.3%; participants with T2D in TODAY: 8.7% vs 9.3%). The T1D group incurred higher median (IQR) monthly out-of-pocket expenses than the T2D group ($74.50 [$10.00-$309.00] vs $10.00 [$0-$74.50]). Conclusions and Relevance: Results of this study suggested that lack of health care coverage and of an established source of diabetes care were associated with significantly higher HbA1c levels for participants with T1D, but inconsistent results were found for participants with T2D. Increased access to diabetes care (eg, through Medicaid expansion) may be associated with improved health outcomes, but additional strategies are needed, particularly for individuals with T2D.

ISPAD Clinical Practice Consensus Guidelines 2022: Type 2 diabetes in children and adolescents.

Since the 2018 ISPAD guidelines on this topic, follow-up of large cohorts from around the globe have continued informing the current incidence and prevalence of co-morbidities and complications in young adults with youth-onset type 2 diabetes (T2D). This chapter focuses on the risk factors, diagnosis and presentation of youth-onset T2D, the initial and subsequent management of youth-onset T2D, and management of co-morbidities and complications. We include key updates from the observational phase of the multi-center Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) clinical trial, the SEARCH for Diabetes in Youth (SEARCH) study and new data from the Restoring Insulin Secretion (RISE) study, a head-to-head comparison of youth onset vs adult-onset T2D. We also include an expanded section on risk factors associated with T2D, algorithms and tables for treatment, management, and assessment of co-morbidities and complications, and sections on recently approved pharmacologic therapies for the treatment of youth-onset T2D, social determinants of health, and settings of care given COVID-19 pandemic.

The Relationship Between Continuous Glucose Monitoring and OGTT in Youth and Young Adults With Cystic Fibrosis.

CONTEXT: Early glucose abnormalities in people with cystic fibrosis (PwCF) are commonly detected by continuous glucose monitoring (CGM). Relationships between these CGM abnormalities and oral glucose tolerance testing (OGTT) in PwCF have not been fully characterized. OBJECTIVE: This work aimed to determine the relationship between CGM and common OGTT-derived estimates of ß-cell function, including C-peptide index and oral disposition index (oDI) and to explore whether CGM can be used to screen for OGTT-defined prediabetes and cystic fibrosis-related diabetes (CFRD). METHODS: PwCF not on insulin and healthy controls aged 6 to 25 years were enrolled in a prospective study collecting OGTT and CGM. A subset underwent frequently sampled OGTTs (fsOGTT) with 7-point glucose, insulin, and C-peptide measurements. Pearson correlation coefficient was used to test the association between select CGM and fsOGTT measures. Receiver operating curve (ROC) analysis was applied to CGM variables to determine the cutoff optimizing sensitivity and specificity for detecting prediabetes and CFRD. RESULTS: A total of 120 participants (controls = 35, CF = 85), including 69 with fsOGTTs, were included. CGM coefficient of variation correlated inversely with C-peptide index (Cpeptide30-Cpeptide0/Glucose30-Glucose0) (r = -0.45, P < .001) and oDIcpeptide (C-peptide index)(1/cpep0) (r = -0.48, P < .0001). In PwCF, CGM variables had ROC - areas under the curve ranging from 0.43 to 0.57 for prediabetes and 0.47 to 0.6 for CFRD. CONCLUSION: Greater glycemic variability on CGM correlated with reduced ß-cell function. However, CGM performed poorly at discriminating individuals with and without OGTT-defined CFRD and prediabetes. Prospective studies are now needed to determine how well the different tests predict clinically relevant nonglycemic outcomes in PwCF.

Two-Year Treatment With Metformin During Puberty Does Not Preserve ß-Cell Function in Youth With Obesity.

CONTEXT: Youth-onset type 2 diabetes is a disease of pubertal onset, associated with additional burden of pubertal insulin resistance on the ß-cell. OBJECTIVE: Evaluate the impact of metformin treatment during puberty, a critical window of cardiometabolic change, on insulin sensitivity (Si) and compensatory ß-cell response in youth with obesity. SETTING: Pediatric academic hospital clinical translational research center. PARTICIPANTS: Healthy youth in early puberty [Tanner stage (T) 2-3] with normoglycemia and obesity (n = 44). INTERVENTION: Double-blinded placebo-control trial of metformin during puberty (until T5). MAIN OUTCOME MEASURES: Insulin sensitivity (Si), insulin response [acute insulin response to glucose (AIRg)], and disposition index (DI), estimated from frequently sampled intravenous glucose tolerance testing; body fat (dual X-ray absorptiometry); and other laboratory parameters, collected at baseline, T4, and T5. Placebo-subtracted treatment effect was calculated using linear mixed models. RESULTS: At T5, metformin treatment, adjusting for sex, race, and baseline value, was associated with improved BMI z-score (-0.44 ±â€…0.16, P = 0.02), percentage body fat (%body fat; -3.4 ±â€…1.2%, P = 0.06), and waist circumference (-11.3 ±â€…3.2cm, P = 0.003). There were no significant treatment effects at T5 on Si or secretion: Si (0.85 ±â€…0.87 × 10-4/min-1/µIU/mL, P = 0.34), AIRg (-259 ±â€…386 µIU/mL, P = 0.51), or DI (508 ±â€…802 × 10-4/min-1, P = 0.53). High baseline DI predicted longitudinal decline in DI. CONCLUSIONS: Two years of metformin treatment in obese youth during puberty improved BMI and body fat, but not Si or ß-cell function. Of note, high DI in early puberty may be predictive of later decline in DI. Further studies are needed to develop strategies for preservation of ß-cell function in youth at risk for type 2 diabetes.

Puberty Is Associated with a Rising Hemoglobin A1c, Even in Youth with Normal Weight.

Our objective was to explore the longitudinal trajectory of hemoglobin A1c (HbA1c) in well-characterized youth (n = 84) with normal weight and obesity during puberty. HbA1c rose from early puberty to Tanner stage 5, even in healthy, normal weight youth, revealing important implications for defining normal glycemia and prediabetes in adolescents.

Delayed glucose peak and elevated 1-hour glucose on the oral glucose tolerance test identify youth with cystic fibrosis with lower oral disposition index.

BACKGROUND: Alternate methods for characterizing oral glucose tolerance tests (OGTT) have emerged as superior to the 2-hour glucose in identifying individuals at risk for type 2 diabetes. The significance of these methods in cystic fibrosis (CF) is unclear. We compared 3 OGTT classifications in youth with CF: 1. curve shape (biphasic vs. monophasic), 2. time to glucose peak (≤30minutes vs. >30minutes), 3. 1-hour glucose (1hG) <155 mg/dL vs. ≥155 mg/dL to traditional OGTT criteria to determine which best identifies lower oral disposition index (oDI), pulmonary function, and body mass index (BMI). METHODS: Youth 10-18 years with CF, not on insulin, underwent 2-hour OGTT. Glucoses were classified by traditional criteria and 3 alternate methods as normal (biphasic curve, glucose peak ≤30minutes, and/or 1hG <155 mg/dL) or abnormal (monophasic curve, glucose peak >30minutes, and/or 1hG ≥155 mg/dL). oDI was calculated [1/fasting insulin*(ΔInsulin0-30 min/ΔGlucose0-30 min)]. Mean oDI, BMI, forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC) were compared by OGTT classification. RESULTS: Fifty-two youth with CF participated (mean±SD age 13±4years; 37% male; BMI z-score 0.0±0.8; FEV1 88±16.3%; FVC 97±14.8%). Late time to peak glucose and 1hG ≥155 mg/dL identified individuals with lower oDI (p=0.01); traditional OGTT criteria for prediabetes did not. No OGTT classification identified individuals with worse BMI nor pulmonary function. oDI was not associated with BMI, FEV1, or FVC. CONCLUSIONS: Alternate OGTT measures including time to peak glucose and 1hG better identify oDI abnormalities than traditional criteria. Further studies are required to determine whether these alternate methods identify individuals with CF at risk for future clinical decline.

Withdrawal of medications leads to worsening of OGTT parameters in youth with impaired glucose tolerance or recently-diagnosed type 2 diabetes.

BACKGROUND: The RISE Pediatric Medication Study compared strategies for preserving ß-cell function, including a 9-month follow-up after treatment withdrawal to test treatment effect durability. OBJECTIVE: Evaluate OGTT measures of glucose and ß-cell response through 12 months of intervention and 9 months of medication washout. PARTICIPANTS: Youth (n = 91) aged 10 to 19 years with BMI ≥85th percentile and impaired glucose tolerance (IGT) or recently diagnosed type 2 diabetes (T2D). METHODS: A multicenter randomized clinical trial comparing insulin glargine for 3 months followed by metformin for 9 months (G→Met) or metformin alone (Met) for 12 months. We report within-group changes from baseline to end of medication intervention (M12), baseline to 9 months post-medication withdrawal (M21), and end of medication (M12) to M21. OGTT C-peptide index [CPI] paired with 1/fasting insulin evaluated ß-cell response. RESULTS: At M12, both treatments were associated with stable fasting glucose (G→Met baseline 6.0 ± 0.1 vs M12 5.9 ± 0.2 mmol/L, P = .62; Met baseline 6.1 ± 0.2 vs M12 6.0 ± 0.2 mmol/L, P = .73) and 2-hour glucose (G→Met baseline 10.2 ± 0.4 vs M12 9.3 ± 0.5 mmol/L, P = .03; Met baseline 10.2 ± 0.4 vs M12 10.6 ± 0.6 mmol/L, P = .88). Following medication withdrawal, fasting glucose worsened (G→Met M21 8.6 ± 1.8, P = .004; Met M21 7.8 ± 0.7 mmol/L, P = .003), as did 2-hour glucose (G→Met M21 13.2 ± 1.4, P = .002; Met M21 13.1 ± 1.2 mmol/L, P = .006), associated with declines in ß-cell response. CONCLUSIONS: G→Met and Met were associated with stable glucose measures during 12 months of treatment in youth with IGT or recently diagnosed T2D. Glucose and ß-cell response worsened post-medication withdrawal, suggesting treatment must be long-term or alternative treatments pursued.

Depression in Girls With Obesity and Polycystic Ovary Syndrome and/or Type 2 Diabetes.

OBJECTIVES: Polycystic ovary syndrome (PCOS) is a common reproductive/metabolic condition associated with obesity, type 2 diabetes (T2D) and depression in adult women. Depression in adults is related to PCOS dermatologic manifestations. Adolescents with obesity with or without T2D have elevated depression symptoms, but data from youth with PCOS and obesity with/without T2D are limited. METHODS: Our study included girls, aged 11 to 17 years, with obesity and PCOS, PCOS+T2D or T2D, who were newly seen in an obesity complications clinic after March 2016. All participants had Center for Epidemiologic Studies-Depression (CES-D, 20 items) scores obtained within 6 months of PCOS or T2D diagnosis. Data on history of psychiatric diagnosis and treatment, metabolic syndrome and severity of acne and hirsutism were collected through chart review. RESULTS: One hundred five girls (47 with PCOS, 14 with PCOS+T2D, 44 with T2D) had similar age (15±1.8 years) and body mass index z scores (2.2±0.4). CES-D scores ≥16, indicating elevated depression symptoms, and CES-D scores ≥24, indicating severe depression symptoms, were observed in 60% and 30% of girls with PCOS, 78% and 71% of those with PCOS+T2D and 39% and 21% of those with T2D, respectively (p<0.0001 for both cutpoints). A higher CES-D score was not associated with severity of hirsutism or acne (p>0.05 for both). CONCLUSIONS: Adolescents with PCOS and obesity have higher rates of elevated depression symptoms compared with girls with T2D, which is not related to worse dermatologic symptoms. Because depression may impact both PCOS and T2D management and adherence to therapy, greater efforts should be made to screen for and address mental health in adolescents with PCOS and obesity, especially if T2D is present.

High prevalence of cardiometabolic risk features in adolescents with 47,XXY/Klinefelter syndrome.

Klinefelter syndrome (KS) occurs in 1:600 males and is associated with high morbidity and mortality due to diabetes and cardiovascular disease. Up to 50% of men with KS have metabolic syndrome, a cluster of features conferring increased risk for diabetes and cardiovascular disease. These cardiometabolic (CM) risk features have not been studied in adolescents with KS. The objective of this cohort study was to compare CM risk features in adolescents with KS to controls matched for sex, age, and BMI z score. Fifty males with KS (age 10-17 years) were well-matched to male controls (n = 50) for age (14.0 ± 1.7 vs. 14.0 ± 1.5 years) and BMI z score (0.3 ± 1.3 vs. 0.4 ± 1.2). Three CM risk features were present in 30% of adolescents with KS compared to 12% of controls (RR 2.5, 95% CI 1.1-5.9, p = .048). The KS group had significantly lower HDL cholesterol (p = .006), higher triglycerides (p < .001), and greater waist circumference percentile (p < .001). Despite a normal BMI, the prevalence of CM risk features was very high in adolescents with KS, particularly for central adiposity and dyslipidemia. The pathophysiology of this metabolic profile independent of obesity needs further investigation to facilitate prevention of the high morbidity of cardiovascular disease and diabetes in this population. ClinicalTrials.gov identifiers: NCT01585831 and NCT02723305.

The Impact of Obesity On Insulin Sensitivity and Secretion During Pubertal Progression: A Longitudinal Study.

CONTEXT: Physiologic changes in glucose metabolism are well-described to occur during puberty. However, there are important gaps in understanding the interaction between obesity and the normal physiologic changes during puberty, as well as how these changes could contribute to the increased risk of comorbidities, such as type 2 diabetes and dyslipidemia, in youth with obesity. OBJECTIVE: The objective of this study was to compare longitudinal changes in insulin sensitivity (Si) and secretion during pubertal progression in youth with obesity versus those with normal weight. DESIGN: Longitudinal observational study evaluating youth from early puberty (Tanner [T]2-T3) until puberty completion (T5). SETTING: Pediatric academic hospital Clinical Translational Research Center. PARTICIPANTS: Pubertal youth with normal weight (n = 47; 22 female, 25 male) and obesity (n = 37; 23 female, 14 male). MAIN OUTCOME MEASURES: Si, insulin response (acute insulin response to glucose, AIRg) and disposition index (DI) by intravenous glucose tolerance test at baseline (T2-T3), T4, and T5. RESULTS: Youth with obesity had significantly lower Si and higher AIRg at each time point (P < 0.001), but DI was similar between the groups. There were no group differences in trajectory of Si, AIRg or DI over time. Leptin, insulin-like growth factor-1, and obesity were most strongly associated with Si and AIRg at all time points. CONCLUSIONS: Obesity significantly impacts Si during puberty, even at the earliest stages. However, in general, obese youth have adequate ß-cell compensation for the significantly reduced Si of puberty. Future studies are needed to better predict the subset of youth who fail to maintain ß-cell compensation during puberty.

Monogenic Diabetes: From Genetic Insights to Population-Based Precision in Care. Reflections From a Diabetes Care Editors' Expert Forum.

Individualization of therapy based on a person's specific type of diabetes is one key element of a "precision medicine" approach to diabetes care. However, applying such an approach remains difficult because of barriers such as disease heterogeneity, difficulties in accurately diagnosing different types of diabetes, multiple genetic influences, incomplete understanding of pathophysiology, limitations of current therapies, and environmental, social, and psychological factors. Monogenic diabetes, for which single gene mutations are causal, is the category most suited to a precision approach. The pathophysiological mechanisms of monogenic diabetes are understood better than those of any other form of diabetes. Thus, this category offers the advantage of accurate diagnosis of nonoverlapping etiological subgroups for which specific interventions can be applied. Although representing a small proportion of all diabetes cases, monogenic forms present an opportunity to demonstrate the feasibility of precision medicine strategies. In June 2019, the editors of Diabetes Care convened a panel of experts to discuss this opportunity. This article summarizes the major themes that arose at that forum. It presents an overview of the common causes of monogenic diabetes, describes some challenges in identifying and treating these disorders, and reports experience with various approaches to screening, diagnosis, and management. This article complements a larger American Diabetes Association effort supporting implementation of precision medicine for monogenic diabetes, which could serve as a platform for a broader initiative to apply more precise tactics to treating the more common forms of diabetes.

Normal Hemoglobin A1c Variability in Early Adolescence: Adult Criteria for Prediabetes Should Be Applied with Caution.

American Diabetes Association adult criteria are used to screen youth for diabetes, but little is known about normal glycemia in youth. In the HEALTHY Study (total n = 8814), hemoglobin A1c was ≥5.7% in 2% of normal weight youth. This suggests need for cautious interpretation of prediabetes hemoglobin A1s in youth.

Evaluation of the longitudinal change in health behavior profiles across treatment groups in the TODAY clinical trial.

BACKGROUND: Individual health behaviors (ie, eating habits and sedentary lifestyle) are associated with type 2 diabetes (T2D). Health behavior profiles specific to adolescents with T2D have not been described. OBJECTIVE: To identify health behavior profiles in adolescents with T2D and examine how these profiles change over time. METHODS: Diet (via food frequency questionnaire) and activity behaviors (via 3-day physical activity recall) examined at baseline, 6 months, and 24 months from participants in the the Treatment Options for T2D in Adolescents and Youth (TODAY) study were used for this analysis. Latent profile analysis identified profiles of health behaviors within three time points, and latent transition probabilities were estimated to examine the change from baseline to 6 months (n = 450) and baseline to 24 months (n = 415). Multinomial logistic regressions were used to examine if the assigned TODAY treatment group (Metformin [Met], Met + Rosiglitazone [Rosi], or Met + Lifestyle) predicted change in health behavior profiles. RESULTS: Three profiles emerged: "most sedentary," "healthy eaters," and "active and eat most." At 6 months, 50% of males and 29% of females in the Met + Lifestyle treatment group improved in their health behavior profile. Among males only, the Met + Lifestyle treatment group were more likely to improve their profiles from baseline to 6 months (P = .01). CONCLUSIONS: Three health behavior profiles emerged and shifted over time. A high quality, lifestyle intervention had little effect on improving health behavior profiles. Optimizing outcomes in youth with T2D might require more robust and multifaceted interventions beyond family-level lifestyle, including more extensive psychosocial intervention, novel medication regimen, or bariatric surgery.

Testosterone Treatment in Infants With 47,XXY: Effects on Body Composition.

CONTEXT: Boys with XXY have greater adiposity and a higher risk of cardiovascular disease. Infants with XXY have lower testosterone concentrations than typical boys, but no studies have evaluated adiposity in infants with XXY or the physiologic effects of giving testosterone replacement. OBJECTIVE: To determine the effect of testosterone on body composition in infants with XXY. DESIGN: Prospective, randomized trial. SETTING: Tertiary care pediatric referral center. PARTICIPANTS: 20 infants 6 to 15 weeks of age with 47,XXY. INTERVENTION: Testosterone cypionate 25 mg intramuscularly monthly for three doses vs no treatment. MAIN OUTCOME MEASURES: Difference in change in adiposity (percent fat mass z scores); other body composition measures, penile length, and safety outcomes between treated and untreated infants; and comparison with typical infants. RESULTS: The increase in percent fat mass (%FM) z scores was greater in the untreated group than in the treated group (+0.92 ± 0.62 vs -0.12 ± 0.65, P = 0.004). Increases in secondary outcomes were greater in the testosterone-treated group for total mass, fat-free mass, length z score, stretched penile length, and growth velocity (P < 0.002 for all). At 5 months of age, adiposity in untreated infants with XXY was 26.7% compared with 23.2% in healthy male infants of the same age (P = 0.0037); there was no difference in %FM between the treated XXY boys and controls. Reported side effects were minimal and self-limited; no serious adverse events occurred. CONCLUSIONS: Adiposity of untreated infants was 15% greater than that of male controls by 5 months of age. Testosterone treatment for infants with XXY resulted in positive changes in body composition.

cgmanalysis: An R package for descriptive analysis of continuous glucose monitor data.

Continuous glucose monitoring (CGM) is an essential part of diabetes care. Real-time CGM data are beneficial to patients for daily glucose management, and aggregate summary statistics of CGM measures are valuable to direct insulin dosing and as a tool for researchers in clinical trials. Yet, the various commercial systems still report CGM data in disparate, non-standard ways. Accordingly, there is a need for a standardized, free, open-source approach to CGM data management and analysis. A package titled cgmanalysis was developed in the free programming language R to provide a rapid, easy, and consistent methodology for CGM data management, summary measure calculation, and descriptive analysis. Variables calculated by our package compare well to those generated by various CGM software, and our functions provide a more comprehensive list of summary measures available to clinicians and researchers. Consistent handling of CGM data using our R package may facilitate collaboration between research groups and contribute to a better understanding of free-living glucose patterns.

Screening for cystic fibrosis-related diabetes and prediabetes: Evaluating 1,5-anhydroglucitol, fructosamine, glycated albumin, and hemoglobin A1c.

OBJECTIVE: Dysglycemia is prevalent in cystic fibrosis (CF) but screening with annual oral glucose tolerance tests (OGTT) can be burdensome. We investigated alternate glycemic markers-hemoglobin A1c (HbA1c), 1,5-anhydroglucitol (1,5AG), fructosamine (FA), and glycated albumin (GA)-as screening tests for CF-related diabetes (CFRD) and pre-diabetes (CFPD) in youth with CF as defined by the gold-standard OGTT 2-hour glucose (2hG). METHODS: Youth 10 to 18 years with CF had a 1,5AG, FA, GA, HbA1c, and 2-hour OGTT collected. Correlations between all glycemic markers and 2hG were evaluated. Area under the receiver operative characteristic (ROC-AUC) curves were generated. Optimal cut points for predicting CFPD (2hG ≥ 140 mg/dL) and CFRD (2hG ≥ 200 mg/dL) were determined. RESULTS: Fifty-eight youth with CF were included (2hG < 140, n = 16; CFPD, n = 33; CFRD, n = 9; 41% male, mean ± SD age 14.2 ± 3.6 years, BMI z-score 0.0 ± 0.8, % predicted forced expiratory volume in 1 second [FEV1] 89.9 ± 15.1, % predicted forced vital capacity [FVC] 103.2 ± 14.6). ROC-AUC's for all alternate markers were low for CFPD (0.52-0.67) and CFRD (0.56-0.61). At a cut point of 5.5%, HbA1c had 78% sensitivity (95% CI: 0.45-0.94) and 41% specificity (95% CI: 0.28-0.55) for identifying CFRD, correlating to a ROC-AUC of 0.61 (95% CI: 0.42-0.8). CONCLUSIONS: All alternate markers tested demonstrate poor diagnostic accuracy for identifying CFRD by 2hG.