YSI Values Research Articles

The ASPIRE Study: Design and Methods of an In-Clinic Crossover Trial on the Efficacy of Automatic Insulin Pump Suspension in Exercise-Induced Hypoglycemia

The Paradigm®Veo™ System includes a low glucose suspend (LGS) feature which suspends insulin delivery when a prespecified glucose threshold setting is reached by the associated continuous glucose monitoring (CGM) sensor. The ASPIRE (Automation to Simulate Pancreatic Insulin REsponse) study is a multicenter, in-clinic, randomized, crossover study to examine the efficacy of LGS in exercise-induced hypoglycemia. Insulin-pump users underwent two separate exercise sessions, one with the LGS feature set to suspend insulin (LGS-on) when the CGM-detected glucose concentration was ≤ 70 mg/dl and one with the LGS feature off. Exercise sessions were conducted after an overnight fast and with initial plasma glucose level as measured by the YSI 2300 STAT Plus glucose analyzer (YSI) of 100-140 mg/dl. Subjects exercised until their YSI value fell to ≤ 85 mg/dl; subsequent YSI values <70 mg/dl were recorded for up to 4 h to measure the duration and nadir of hypoglycemia. The protocol required that subjects with YSI values <50 or >300 mg/dl were rescued with carbohydrates or insulin, respectively, based on the provider's recommendation. The primary end point was comparison of duration and severity of hypoglycemia between LGS-on and LGS-off sessions. Secondary end points included areas under the glucose concentration curve, CGM sensor accuracy, and last YSI glucose. Device- and procedure-related adverse events and serious adverse events were recorded. Fifty adults and teenagers (17-58 years) with type 1 diabetes were randomized. Study completion is expected in November 2011.

FreeStyle Mini™ Blood Glucose Results Are Accurate and Suitable for Use in Glycemic Clamp Protocols

We assessed the accuracy of the FreeStyle Mini (FSM) meter for use in glycemic clamp and meal protocols in comparison with the HemoCue Glucose 201 DM Analyzer (HemoCue) and the YSI 2300 STAT Glucose Oxidase Analyzer (YSI). Seven volunteers with type 2 diabetes mellitus, 35-69 years old, underwent a frequently sampled meal test and a graded hyperglycemic test, on two separate days, with one of the volunteers undergoing each test twice. Samples for glucose measurements were obtained from arterialized venous blood. A total of 420 samples (with glucose levels ranging from 63 to 388 mg/dl) were available for comparison. On average, 10 measurements were available for every 5 mg/dl increment in glucose level in the range of 130-310 mg/dl. Blood glucose measurements were done on each sample with the FSM, HemoCue, and YSI. FreeStyle Mini blood glucose values correlated closely with the YSI readings. Of the FSM measurements, 99.0% were within the Clarke error grid zone A; 51.3%, 84.7%, and 96.2% of the FSM readings were within 5%, 10% and 15% of the YSI values, respectively. The FSM was significantly more accurate than the HemoCue (84.7% vs 76.6% of results within 10% of the YSI results; p = .0038). The mean average relative difference of the FSM (5.8%) was also significantly lower than that of the HemoCue (6.8%; p = .0013) The FSM provides accurate results and constitutes a suitable alternative for bedside blood glucose measurements in experimental procedures, helping to reduce sample size, turnaround time, and cost.

COMPARISON OF THE ACCUSPORT, YSI 1500, AND YSI 23L LACTATE ANALYZERS DURING PROGRESSIVE CYCLE ERGOMETER EXERCISE

195 Blood lactate has been used to evaluate an athlete's lactate threshold and document progress made during training. Routine evaluation of athletes“in the field” has been limited, however, due to lack of a simple portable instrument. The purpose of the present study was to compare the hand held Accusport portable lactate analyzer to both the YSI 1500 Sport and YSI 23L lactate analyzers. A total of 16 subjects completed a progressive incremental steady state cycle ergometer protocol to exhaustion. Finger capillary blood was collected at 100, 150, 175W, maximal workload (Mean = 323W), and 5 minutes into a passive recovery. Aliquots of the same sample were evaluated by all three instruments. Accusport measurements were obtained in duplicate by placing a single drop of blood on the application strip and by pipetting a 25 ul sample on the application strip. A 25 ul sample was used for both the YSI instruments. Lactate values (mmol/l) are presented below: TableTableThe YSI instruments produced similar results. Likewise, the Accusport values were similar. However, the Accusport values were consistently greater(p<0.05) than the YSI values at the same workload. Although the Accusport is less expensive and more portable than either the YSI 1500 or 23L, the greater values would define a lactate threshold to be at a lower power output.