Quantitative Research Critique By Elisabeth Bryant
A Paper Submitted in partial fulfillment of the requirements for NU 533 Advanced Nursing Research University of South Alabama College of Nursing Spring 2011
2 Quantitative Research Critique
This is a critique of the quantitative research article titled Influence of Obesity and Type 2 Diabetes on Gluconeogenesis and Glucose Output in Humans studied by Amelia Gastaldelli, Simona Baldi, Maura Pettiti, Elana Tischi, Stefania Camastra, Andrea Natali, Bernard R. Landau and Ele Ferrannini. This article was published in the journal Diabetes in 2000 volume 49 issue 8 pages 1367-1373. Purpose, PICO and Level of Evidence The investigators wanted to study individuals who were obese and those who had type II diabetes to determine the percentage of gluconeogenesis to glucose release and how it is related to the degree of obesity and diabetes. This was done due to the lack of research on how factors such as sex, age, obesity and degree of glycemic control effect gluconeogenesis. The experiment was conducted with a control group of individuals that were not considered obese or diabetic. The investigators found that plasma glucagon levels were higher in diabetic participants and these results were positively related to endogenous glucose output. They also found that obese patients had higher levels of plasma insulin that was not related to fluxes in glucose. Research Design and Method The investigators used experimental design to answer the study question. First, they had the participants drink a predetermined amount of water with a tracer added to it. This methodology was mentioned as a possible area of controversy later in the article. Secondly, the individuals fasted overnight. After the fast, the participants came to the hospital where the experiment was being conducted by 9 am. Here indwelling venous catheters were placed in both arms. One was placed in the antecubital for the glucose isotope infusion and
another in the opposite wrist. The glucose isotope was then infused for 120 minutes for the nondiabetic participants and was extended up to 180 minutes for the diabetic participants. The infusion time for the diabetic patients was extended in proportion to the increase in fasting plasma glucose. Blood samples were taken from each participant before the infusion began to measure the levels of glucose isotope, insulin levels and glucagon concentrations. Samples of blood were then taken every 10 minutes for the last 20 minutes of the infusion to measure the same levels. The investigators also measured carbon 5 and natural glucose enrichment in blood samples taken the day before the study and measured these levels again at the end of the isotope infusion. One final blood sample was taken to measure the carbon 5 enrichment after 12 hours fasting. There are independent variables that could not be controlled. These items were such things as waist circumference, waist to hip circumference, fasting plasma glucose and others. The dependent variables were controlled to some degree by means of withholding oral medications from the diabetic patients and treating their plasma glucose by means of diet alone for four weeks prior to the experiment. Insulin dependent diabetics were excluded from the study and nondiabetic subjects were not taking any medications that were known to affect plasma glucose levels. Literature Review The investigators perform a literature review which is discussed in the introduction of the research. In this review, the first 19 items on the reference list are reviewed. The studies that were reviewed were state of the art at the time and had dates ranging from 1983 to 1998.
There was also discussion of the limitations of the previous studies and the need for the study the investigators were undertaking. The author stated,...