Where Should New Research Go?
Challenges in evaluating the evidence regarding the effects of carbohydrate intake on metabolic parameters in diabetes management include variability in study methodology eg, adherence measurement with regard to carbohydrate intake, small study samples for intervention trials, low retention rates, and confounding by weight loss. The intention-totreat analysis has been criticized by advocates who focus on the best case scenario results using data from the completers – highly adherent individuals who “stick to the lowcarbohydrate intervention plan.” [64]. This approach may yield insights about mechanism of action within the low carbohydrate treatment but does not address predictors of response in the general population. Examination of how economic, cultural, and clinical variables are related to adherence and study outcomes may yield valuable insights. New research needs to address the impacts of lowering carbohydrate on a wide range of biomarkers including lipids, insulin resistance, liver metabolism, gut hormones, inflammation, and glycemia. The clinical significance of biomarkers is an important area to address the long-term outcomes. The availability of carbohydrate can be affected by the co-ingestion of fiber. The research needs to include properties of such a fermentation which affects gut hormone secretion and their wide-spread metabolic effects. As research generates new information about the effects of carbohydrate and fiber, the food industry will generate new research to reformulate and create new food products and nutraceuticals. As genomic research advances, more research that examines genetic variability in response to dietary carbohydrate will provide insights for tailoring nutrition advice. While prior research has explored the mechanisms underlying the relationship between nutrition and glycemia, future studies are likely to focus on individualizing nutritional intake recommendations by examining how nutrition relates to genetic polymorphism and the endocrine functions of gut hormones such as GLP-1 and PYY with regard to glycemia and other cardiovascular parameters.