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Fiber, protein play important roles in glycemic control
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Increasing dietary fiber intake can help adults with type 1 diabetes lower blood glucose levels, and using protein as a replacement for other macronutrients can reduce glycemic excursions, according to findings published in Diabetic Medicine.
“Dietary intake plays an important role in the glycemic control of people with type 1 diabetes. Current evidence in this field is, however, somewhat mixed; for example, analyses are frequently not adjusted for fiber intake,” Per-Henrik Groop, MD, DMSc, professor of nephrology at the University of Helsinki in Finland, and colleagues wrote. “Moreover, under isoenergetic conditions, an increase in the intake of one macronutrient is accompanied by a decrease in the intake of another macronutrient(s).”
Groop and colleagues conducted an observational, cross-sectional study using data from the Finnish Diabetic Nephropathy study. A total of 1,000 participants with type 1 diabetes (58% women; median age, 47 years; mean HbA1c, 7.9%) were included in the analysis. Dietary intake was measured by questionnaires, including two 3-day food records, which were completed at least 2 months apart. Self-reported measures of physical activity, insulin dosing and self-monitored blood glucose were also collected.
The researchers found that mean blood glucose concentration was negatively associated with intake of fiber, carbohydrate, polyunsaturated fatty acids and protein, whereas positive associations were found with total fat, saturated fatty acids and monounsaturated fatty acids. Fiber consumption, specifically, had a significant lowering effect on blood glucose (beta = –0.428; 95% CI, –0.624 to –0.0231). Consumption of carbohydrates (beta = 0.011; 95% CI, 0.002-0.02), alcohol (beta = 0.013; 95% CI, 0.003-0.023) and monosubstituted fatty acids (beta = 0.012; 95% CI, 0.001-0.023) increased blood glucose variability.
The effect of macronutrient substitutions on blood glucose variability was also examined. Blood glucose levels were higher when fats were consumed in place of proteins (beta = 0.023; 95% CI, 0.009-0.037) and when saturated fatty acids replaced monounsaturated (beta = 0.027; 95% CI, –0.011 to 0.64) or polyunsaturated fatty acids (beta = 0.034; 95% CI, 0.008-0.063). However, the researchers noted that these results were mediated when fiber intake was incorporated. Conversely, replacing carbohydrates (beta = –0.026; 95% CI, –0.04 to –0.013), fats (beta = –0.018; 95% CI, –0.033 to –0.004) or alcohol (beta = –0.026; 95% CI, –0.045 to –0.006) with increased protein intake led to lower blood glucose variability.
“Fiber intake was the only dietary variable associated with lower mean SMBG concentrations. The suggested mechanisms through which dietary fiber is thought to exert its glycemia-reducing effects include, but may not be restricted to, delayed gastric emptying, reduced accessibility of a-amylase to its substrates as a result of fiber-induced increase in the viscosity of the partly digested food mass and increasing insulin sensitivity related to short-chain fatty acid production by the gut microbiota,” the researchers wrote. “Interestingly, the self-reported median fiber intake in the present study fell below the Finnish dietary recommendations, suggesting that increase in fiber intake could be beneficial in this population.” – by Phil Neuffer
Disclosures: Groop reports that he received research grants from Eli Lilly and Roche, and is an advisory board member for AbbVie, AstraZeneca, Boehringer Ingelheim, Cebix, Eli Lilly, Janssen, MSD, Medscape, Novartis, Novo Nordisk and Sanofi. Please see the study for all other authors’ relevant financial disclosures.
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