Two major goals in the treatment of diabetic patients are to improve metabolic control and the serum lipid profile. Dietary modifications can affect the metabolic control and the lipid profile in NIDDM patients favorably by regulating blood glucose, by reducing total cholesterol, triglycerides, and low density lipoprotein-cholesterol and by elevating high density lipoprotein-cholesterol levels. However, there is disagreement in the research literature about the magnitude and direction of these changes as a result of specific dietary manipulations. Recent literature reviews have synthesized research by using the """"""""traditional"""""""" approach (chronologically arranging and describing the studies, perhaps by subtopic) which may result in subjective, non-replicable conclusions. consequently, the relationships among variables such as treatment length (trial), diet composition, subject characteristics, experimental design quality, body weight changes, metabolic control, and how they contribute to changes in blood glucose and serum lipid levels are not clear. In this proposed project, the meta-analytic approach will be used to synthesize research on the relationships among variables associated with dietary intervention, blood glucose, and the lipid profile in NIDDM patients. Meta-analysis is a method for pooling results of separate studies in a systematic, explicit, comprehensive, and replicable manner. It is a quantitative approach for increasing statistical power for primary end points and subgroups, resolving uncertainty when studies disagree, improving estimates of effect sizes, and answering questions not posed at the start of individual trials.
The specific aims are to: (1) statistically integrate (meta- analysis) existing research studies on the effects of diet therapy on metabolic control and serum lipid and lipoprotein levels in human subjects with NIDDM; (2) determine the overall magnitude and direction of changes in metabolic control and serum lipid levels as a result of diet therapy; (3) determine the interrelations (interactions) among glycemic control and changes in serum lipid levels and variables such as duration of diet therapy, diet composition, experimental design quality, subject's gender, subject type, glycemic index, and obesity; (4) compare similar diets in NIDDM and """"""""normal"""""""" subjects; and (5) compile a unique data base that will be made available to researchers and clinicians interested in the effects of diet therapy on metabolic control and lipid outcomes in NIDDM and normal subjects. The results of this project should provide a clarification of the contributions of diet therapy to changes in metabolic control and the CAD lipid risk factor in humans subjects with NIDDM.
