HbA1c and fasting plasma glucose (FPG) levels are commonly recognized as diagnostic indices for diabetes and glucose intolerance. However, they are not sufficient for clear detection of glucose intolerance in the early stage unless an oral glucose tolerance test (OGTT) is performed. Moreover, even in case of an OGTT, 2-h postprandial plasma glucose (PG) levels, a criterion for glucose intolerance in OGTTs, may not provide complete information regarding glucose tolerance. Whole glucose excursion after OGTT is considered to represent glucose tolerance well, and the glucose area under the curve (AUC) can be an index of glucose excursion. However, few studies have investigated measurement of the glucose AUC in glucose intolerance screening. In the present study, data from 520 OGTTs were analyzed to define the cutoff value for the glucose AUC for glucose intolerance screening. Our results showed that a cutoff value of 290 mg h/dl for the glucose AUC was highly sensitive and specific (90 and 93 %, respectively) for detecting diabetes, impaired glucose tolerance (IGT), and group at increased risk of diabetes (normal glucose tolerance with 1-h PG levels of C180 mg/dl after glucose load) and showed a better concordance rate than the use of HbA1c, FPG, or 2-h PG levels. Moreover, the cutoff value for the glucose AUC calculated using the diagnostic criteria in the OGTT (305 mg h/dl) was consistent with the value determined from OGTT analysis. These data suggest a possibility that glucose intolerance screening using a glucose AUC cutoff value of 290 mg h/dl could be useful.

The glucose AUC monitoring system using IG provided good estimates of reference PG-AUC and maximum PG level during OGTTs in subjects with and without diabetes. This system provides easy-to-use monitoring of glucose AUC, which is a good indicator of postprandial glucose.

Abbreviations: (ADA) American Diabetes Association, (AUC) area under the curve, (CGM) continuous glucose monitoring, (DM) diabetes mellitus, (FPG) fasting plasma glucose, (IDF) International Diabetes Federation, (IG) interstitial fluid glucose, (IRI) immunoreactive insulin, (ISF) interstitial fluid, (MIET) minimally invasive interstitial fluid extraction technology, (OGTT) oral glucose tolerance test, (PG) plasma glucose, (SMBG) selfmonitoring of blood glucose

These findings validate the adequacy of glucose AUC measurements using MIET. Monitoring glucose using MIET without blood sampling may be beneficial to patients with diabetes.

BackgroundManagement of postprandial hyperglycemia is a key aspect in diabetes treatment. We developed a novel system to measure glucose area under the curve (AUC) using minimally invasive interstitial fluid extraction technology (MIET) for simple monitoring of postprandial glucose excursions. In this study, we evaluated the relationship between our system and continuous glucose monitoring (CGM) by comparing glucose AUC obtained using MIET with that obtained using CGM for a long duration.MethodsTwenty diabetic inpatients wearing a CGM system were enrolled. For MIET measurement, a plastic microneedle array was applied to the skin as pretreatment, and hydrogels were placed on the pretreated area to collect interstitial fluid. Hydrogels were replaced every 2 or 4 hours and AUC was predicted on the basis of glucose and sodium ion levels.ResultsAUC predicted by MIET correlated well with that measured by CGM (r=0.93). Good performances of both consecutive 2- and 4-hour measurements were observed (measurement error: 11.7%±10.2% for 2 hours and 11.1%±7.9% for 4 hours), indicating the possibility of repetitive measurements up to 8 hours. The influence of neither glucose fluctuation nor average glucose level over the measurement accuracy was observed through 8 hours.ConclusionOur system showed good relationship with AUC values from CGM up to 8 hours, indicating that single pretreatment can cover a large portion of glucose excursion in a day. These results indicated possibility of our system to contribute to convenient monitoring of glucose excursions for a long duration.