| Objective:To evaluate the feasibility,safety,and effectiveness of the low-carbohydrate diet(LCD)program("six-word formula")using almonds instead of some carbohydrates in real clinical situations.From the perspective of the almond-based LCD,further explore the possible partial mechanism of this LCD to improve blood glucose.Methods:The study was a prospective randomized controlled trial combined with a qualitative study.Using convenient sampling,from March to October 2019,patients with type 2 diabetes mellitus(T2DM)who met the inclusion exclusion criteria were selected.The subjects were randomly allocated to the LCD group and the low fat diet(LFD)group,and the intervention lasted 12 weeks.The LFD group adopted the low-fat diet recommended by the guidelines.The LCD group diet was based on the LFD with 56g/d of almonds to replace some of the carbohydrates.By understanding the obstacles in the implementation of the LCD program,the distribution of three macronutrients in the LCD program and the compliance of eating almonds,to evaluate the implementability of the LCD program.By observing the occurrence of hypoglycemia and other adverse events during the implementation of LCD program to evaluate it’s safety.To evaluate the effectiveness of the LCD program,fasting blood glucose,2h postmordial blood glucose,glycosylated hemoglobin(HbA1c),blood pressure,body weight,body mass index(BMI),and hypoglycemic drug use were compared between LCD and LFD groups.By detecting the diversity of gut microbiota,the target gut microbiota for producing short chain fatty acids(SCFAs)and the level of fasting plasma glucagon-like peptide 1(GLP-1)before and after intervention in the two groups of patients,the possible partial mechanism of improving blood glucose with almond-based LCD pattern was further explored.Results:A total of 62 patients with T2DM were included in the study,including 30 in the LCD group and 32 in the LFD group.After 12 weeks of intervention,23 in the LCD group and 27 in the LFD group were included in the final statistical analysis.1.Implementability assessment(1)The obstacles to the implementationThere were summarized as three major obstacles:the poor cognition and perception of LCD program,the economic considerations and other limiting factors.(2)Distribution of three macro nutrientsAfter 12 weeks of intervention,the energy supply ratio of carbohydrate:fat:protein in the LCD group(%)was 41:39:20,and that of the LFD group(%)was 59:24:17,all reaching the standard of each dietary pattern.(3)Almond compliance20(86.96%)patients with good compliance and 3(13.04%)patients with poor compliance,and the overall compliance was fair.2.Safety assessment(1)Hypoglycemia eventDuring the 12 weeks of intervention,no hypoglycemia occurred in the patients in the LCD group,and 1(3.7%)patients in the LFD group had hypoglycemia twice.There was no statistical difference between the groups(P>0.05).(2)Other adverse eventsDuring the 12-week intervention period,one patient in the LCD group consciously developed indigestion and bloating after 4 weeks of intervention,and then withdrew;another patient had diarrhea at 7 weeks after the intervention,stopped taking almonds for 5 days,and symptoms disappear,continue to eat almonds to the end of the intervention;no adverse events occurred in the remaining patients.3.Effectiveness assessmentAfter 12 weeks of intervention,HbAlc in the LCD group had statistically significant differences between and within groups(P<0.01);there were no difference in fasting blood glucose,2h postprandial blood glucose,body weight,BMI,and systolic blood pressure between the groups(P>0.05);and there were significant differences within the group(P<0.05);there was no statistical difference in diastolic blood pressure between groups or within groups(P>0.05).There was no significant difference in the adjustment of hypoglycemic agents between the groups(P>0.05).4.Possible partial mechanism of almond-based LCD to improve blood glucose(1)Effect of gut microbiota1)The diversity of gut microbiotaThere were no significant difference in the alpha diversityofgut microbiota between the two groups or within groups(P>0.05).The beta diversity of gut microbiota,there were some differences in gut microbiota structure between the groups.2)Comparison of the relative abundance of Firmicutes and Bacteriodetes and their ratiosAfter 12 weeks of intervention,the relative abundance of Bacteroidetes and the ratio of Bacteroidetes/Firmicutes in the LCD group were significantly higher than that in the LFD group(P=0.001).The relative abundance of Bacteroidetes and the ratio of Bacteroidetes/Firmicutes in the LCD group increased significantly,and the difference was statistically significant compared with the baseline(P<0.01).3)Change of target gut microbiotaAfter 12 weeks of intervention,the relative abundance of Bacteroides and Lachnospira in the LCD group were significantly higher than that in the LFD group,the difference were statistically significant(P<0.01),and there was no differencein the other genus groups(P>0.05).The comparison results within the group found that the relative abundance of Lactobacillus(P=0.04),Bacteroides(P=0.015),and Lachnospira(P<0.01)in the LCD group significantly increased compared to baseline;the relative abundance of Bifidobacterium and Eubacteria were increased,but there were no statistically significance(P>0.05).(2)Effect of fasting plasma GLP-1After 12 weeks of intervention,the fasting plasma GLP-1 concentration in the LCD group was slightly higher than at baseline,while it was decreased in the LFD group,which has a statistically significant difference between the two groups(P=0.003).The fasting plasma GLP-1 concentration did not change significantly before and after the intervention in the LCD group,while in the LFD group,it was significantly lower than at baseline,with a statistically significant difference(P=0.032).Conclusions1.Although there were certain obstacles to the LCD program that replaces some carbohydrates with almonds in real clinical situations,most patients had good compliance with this program,and have higher safety and better effectiveness.It’s a diabetes diet intervention program suitable for clinical application and promotion.2.The study preliminarily demonstrated that the mechanism of improving blood glucose by almond-based LCD may play a hypoglycemic role through the gut microbiota-SCFAsGLP-1 pathway.However,due to the lack of relevant research data on SCFAs,it needs to be demonstrated in subsequent population studies and animal experiments. |
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