Two-hour postprandial test versus one-hour, fifty-gram glucola test as screening tools for gestational diabetes: a critical analysis.

OBJECTIVE: The objective of this study was to compare 2-hour postprandial glucose measurements with the standard 1-hour, 50 gm glucola screen as a predictor of gestational diabetes. STUDY DESIGN: In this prospective study, 448 patients were screened for gestational diabetes mellitus after 20 weeks' gestation. Each patient was instructed to ingest a meal containing at least 100 gm of carbohydrate, and 2 hours later a plasma glucose level was obtained. Shortly after, each patient was given 50 gm glucola followed by a 1-hour glucose measurement. If either screen showed a result of 140 mg/dl or more, a formal 3-hour glucose tolerance test was done. Data were analyzed with use of the receiver operating characteristic curve. RESULTS: Of the 448 patients screened, 39 (8.7%) had a screening result of 140 mg/dl or greater and 16 (3.6%) of these had gestational diabetes mellitus. The receiver operating characteristic curve showed that the 1-hour glucose screen was more predictive of gestational diabetes than the postmeal assessment. The area under the receiver operating characteristic curve (plus or minus the SEM) for the 1-hour glucose test was 0.746 +/- 0.086 (p < 0.005) whereas the 2-hour postprandial test produced an area of 0.524 +/- 0.097 (p = NS). The range of optimal 1-hour glucola discriminatory values was 182 to 190 mg/dl. Thus the critical cutoff value of the 1-hour glucola test that minimizes false-positive results and maximizes true-positive screening for gestational diabetes is 182 mg/dl or greater. CONCLUSIONS: The 1-hour glucola test is a reliable screening test for gestational diabetes mellitus whereas the 2-hour post-prandial test is not.

Long-term seasonal abundance patterns of Helicoverpa zea and Heliothis virescens (Lepidoptera: Noctuidae) in the Texas High Plains.

Bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), male adult (moth) activities were monitored between 1982 and 1995 by using sex pheromone traps in the Texas High Plains. Moths were monitored weekly from early March to mid-November near Lubbock and Halfway, two prominent cotton production areas in the Texas High Plains region. Based on trap captures, the bollworm-budworm complex consisted of approximately 98% bollworms and approximately 2% tobacco budworms. Seasonal activity patterns varied between location for bollworm but not for tobacco budworm. The 14-yr average (+/- SE) bollworm moth abundance (moths per trap per week) at Lubbock was significantly higher (226.5 +/- 10.4) compared with that at Halfway (153.7 +/- 8.1). Correlation analyses showed a significant positive relationship between moth abundance and average weekly temperatures, whereas a significant negative relationship was observed between moth abundance and average weekly wind velocity for both species. Analyses also showed a positive correlation between moth abundance and cumulative degree-days (> 0.0 degrees C) from 1 January. A strong positive relationship was observed between moth abundance and weekly average precipitation for both species. Average weekly abundances were positively correlated between adjacent months during most of the active cotton fruiting season (June-September). However, the relationship between populations that contributed to the overwintering generation and the following spring populations varied between species and study sites. Nevertheless, data from this study indicated that late-season moth catches could be indicative of the dynamics of the early-season moth catches the following year in the High Plains. The mean population abundance curve based on 14-yr averages showed two bollworm population peaks at Lubbock, but only one peak at Halfway. Separate degree-day-based models were developed to describe long-term seasonal abundance patterns of bollworm moths for the Lubbock and Halfway sites.