Noninvasive skin fluorescence spectroscopy is comparable to hemoglobin A1c and fasting plasma glucose for detection of abnormal glucose tolerance.

AIM: We compare performance of noninvasive skin fluorescence spectroscopy (SFS), fasting plasma glucose (FPG), and hemoglobin A1c (A1C) for detection of abnormal glucose tolerance (AGT). METHODS: The NSEEDS trial evaluated SFS, FPG, and A1C in an at-risk population of 479 previously undiagnosed subjects from nine US centers, each of whom received a 75 g, 2 h oral glucose tolerance test (OGTT). Skin fluorescence spectra were collected and analyzed with SCOUT DS® devices. Disease truth was AGT, defined as OGTT ≥140 mg/dl. Abnormal glucose tolerance sensitivity, false positive rate (FPR), and receiver operating characteristic (ROC) curves were computed for each measurement technique. Skin fluorescence spectroscopy reproducibility was also assessed. RESULTS: The AGT sensitivity of SFS was 68.2%, higher than that of FPG (thresholds of 100 and 110 mg/dl) and A1C (thresholds of 5.7% and 6.0%). The FPR of SFS was 37.7%, comparable to A1C at the 5.7% threshold (30.7%). Partial ROC areas of SFS, FPG, and A1C were similar for FPRs of 20-50% (average sensitivities of 64.0%, 59.0%, and 68.6%, respectively). The interday coefficient of variation for SFS was 7.6%. CONCLUSIONS: Skin fluorescence spectroscopy has similar screening performance to FPG and A1C and is a viable approach for detection of AGT.

Cross-sectional evaluation of noninvasively detected skin intrinsic fluorescence and mean hemoglobin a1c in type 1 diabetes.

BACKGROUND: This study evaluated the relationship between skin intrinsic fluorescence (SIF) and long-term mean hemoglobin A1c (HbA1c) in individuals with type 1 diabetes. SUBJECTS AND METHODS: We undertook a cross-sectional analysis of 172 individuals with type 1 diabetes followed longitudinally with HbA1c data available over an average of 16.6 years. SIF was evaluated cross-sectionally using the SCOUT DS device (VeraLight Inc., Albuquerque, NM) and correlated with most recent HbA1c and long-term mean HbA1c. Potential determinants of this relationship, including age, gender, smoking status, duration of diabetes, and renal function, were also evaluated. RESULTS: Age-adjusted skin intrinsic fluorescence significantly correlated with long-term mean HbA1c (R=0.44, P<0.0001). In contrast, there was no significant relationship between SIF and most recent HbA1c (R=0.14, P=0.075). The best-fit model describing the relationship between SIF and mean HbA1c controlled for factors of age, duration of disease, renal function, and site of study conduct. Controlling for these factors was also important in understanding the relationship between most recent HbA1c and SIF. Evaluating longer-term HbA1c data also strengthened the relationship between SIF and mean HbA1c. In the presence of renal dysfunction or damage, as indicated by an estimated glomerular filtration rate of <60 mL/min/1.73 m2 or presence of gross proteinuria, there was no significant correlation between SIF and mean HbA1c. CONCLUSIONS: Noninvasive detection of SIF significantly correlates with long-term mean HbA1c, providing insight into long-term glycemic exposure. Age, duration of diabetes, and renal function are potential contributors to this relationship.

Noninvasive type 2 diabetes screening: clinical evaluation of SCOUT DS in an Asian Indian cohort.

OBJECTIVE: This study evaluated the noninvasive, point-of-care diabetes screening device, Scout DS (VeraLight Inc., Albuquerque, NM) (SCOUT), in a native Asian Indian cohort. RESEARCH DESIGN AND METHODS: SCOUT is a tabletop, skin fluorescence spectrometer that reports a risk score following a 3-4-min noninvasive measurement of a subject's left volar forearm. SCOUT, fasting plasma glucose (FPG), and hemoglobin A(1c) (A1C) were compared for detection of abnormal glucose tolerance (AGT) in a cohort of 256 subjects without previous diagnosis of diabetes or impaired glucose tolerance in Chennai, India. After an overnight fast, a 75-g, 2-h oral glucose tolerance test was administered, and AGT was defined as a plasma glucose value ≥ 140 mg/dL (7.8 mmol/dL). Sensitivity, false-positive rate (FPR), and receiver-operating characteristics area under the curve for AGT detection were computed for SCOUT, FPG, and A1C. Intra-day reproducibility of SCOUT was assessed. RESULTS: SCOUT, FPG, and A1C (at respective thresholds of 50, 110 mg/dL, and 5.7%) exhibited sensitivities of 87%, 32%, and 86%, respectively, and FPR of 52%, 3%, and 58%, respectively. For the 177 subjects receiving a valid SCOUT Diabetes Score on both measurement attempts, the coefficient of variation was 5.8%, and the Pearson correlation was 0.91. A SCOUT score could be obtained on 91% of subjects after two attempts. CONCLUSIONS: The performance of SCOUT is similar to that of A1C, whereas FPG had a much lower sensitivity. SCOUT is an effective tool for AGT screening in Asian Indians.

Skin fluorescence correlates strongly with coronary artery calcification severity in type 1 diabetes.

BACKGROUND: Coronary artery calcification (CAC) is more severe and occurs at an earlier age in type 1 diabetes. Risk factors for this subclinical marker of atherosclerotic burden, like coronary artery disease (CAD) itself, are not fully identified. One postulated mechanism for the increased CAC observed in type 1 diabetes is the accumulation of advanced glycation end products (AGEs). As certain collagen AGEs fluoresce, skin intrinsic fluorescence (SIF) can act as a novel marker of levels of collagen AGEs. We thus sought to determine the relationship between skin intrinsic fluorescence and CAC in type 1 diabetes. METHODS: One hundred five participants in the Pittsburgh Epidemiology of Diabetes Complications study of childhood-onset (age <17 years) type 1 diabetes who had previously undergone electron beam tomography scanning for CAC (80 of whom had follow-up data) had SIF measurements taken using the SCOUT DM (VeraLight, Inc., Albuquerque, NM). Mean age and diabetes' duration were 49 and 40 years, respectively, at the time of SIF measurement. RESULTS: Seventy-one percent of the study participants had some measurable CAC that was univariately (but not after age adjustment) cross-sectionally associated with SIF (odds ratio = 2.51, 1.37-4.59). However, for CAC severity using natural logarithmically transformed scores, SIF was both univariately (P < 0.0001) and multivariably (P = 0.03) associated with CAC. This relationship was independent of age, a history of CAD, renal function, or renal damage. Receiver operator characteristic analyses revealed that the discriminative ability of SIF to detect CAC went from an area under the curve of 71% for the presence of any CAC to 85% for those with a CAC score >400. CONCLUSIONS: The relationship between SIF and CAC appears stronger with more severe calcification. Given the strong relationship of CAC with CAD this finding has important implications and suggests that SIF maybe a useful marker of CAC/CAD risk and potentially a therapeutic target.