Lutgarda Bozzetto

Background/objectives Targeting postprandial glucose response (PPGR) is more effective than lowering fasting plasma glucose in improving glycemic control and reducing cardiovascular risk in individuals with type 2 diabetes (T2D). Continuous glucose monitoring (CGM) has the potential to uncover time-related features of PPGR. This study evaluates the within-subject reproducibility of dynamic PPGR parameters obtained by CGM and explores their potential as independent predictors of glycemic control in T2D. Subjects/methods A total of 102 individuals with T2D underwent a 7-day CGM and consumed a standardized breakfast twice to assess the 4-h glucose response, described by the following parameters: glucose peak—the highest glucose value; time to peak—time of peak occurrence; delta glucose max—the difference between the peak and fasting glucose; nadir—the lowest post-peak glucose value; incremental area under the glucose curve; mean postprandial glucose—the average interstitial glucose concentration. Intraclass correlation coefficients (ICCs) for both single and average measurements with their 95% confidence intervals (CIs), were calculated for PPGR parameters to estimate their within-subject reproducibility. Multivariable linear regression models assessed the independent predictive contribution of PPGR parameters, fasting glucose, and 2-h postprandial glucose on 7-day CGM metrics and HbA1c. Results Moderate to good reproducibility for single measurements was observed for mean glucose (ICC: 0.78, 95%CI 0.69–0.84), glucose peak (ICC: 0.69, 95% CI 0.57–0.78), and nadir (0.74, 95% CI 0.64–0.82). Mean postprandial glucose was the strongest predictor of 7-day time in range (β = −0.772, p < 0.001), 7-day mean glucose (β = 0.800, p < 0.001) and HbA1c (β = 0.434, p < 0.001), whereas the glucose peak was the main predictor of short-term glycemic variability, as reflected by the 7-day coefficient of variation (β = 0.258, p = 0.006) and mean amplitude of glucose excursions (β = 0.613, p < 0.001). Conclusion In individuals with T2D, CGM-derived parameters of PPGR are reproducible and could represent a practical tool to uncover meaningful information about glucose control, which 2-h postprandial glucose fails to predict.

Objective Short-chain fatty acids (SCFA) play a role in modulating glucose metabolism and are influenced by diet. Alterations in the SCFA-producing microbial ecosystem in individuals with type 1 diabetes (T1D) may contribute to impaired glycaemic control. This study investigated the relationships between serum SCFA levels, blood glucose control, and dietary habits in adults with T1D. Design Observational study. Setting The study was conducted at the diabetes outpatient clinic of Federico II University Teaching Hospital, Naples, Italy. Population The study included 198 adults with T1D (100 men and 98 women), aged 18–79 years. Main outcome measures Serum SCFA levels, blood glucose control, assessed by glycated haemoglobin (HbA1c) and continuous glucose monitoring (CGM) metrics, and dietary intake from a 7-day food record. Results SCFA levels showed significant sex-specific differences (p180 mg/dL) (32.2±12.6% vs 41.2±17.2%, low tertile; p=0.011) and improved glucose management indicator (7.1±0.6% vs 7.5±0.6%, low tertile; p=0.027). Regarding eating habits, higher acetate tertiles were associated with higher intakes of total fat (p=0.041), polyunsaturated fatty acids (p=0.049) and monounsaturated fatty acids (p=0.021) in men only. Conclusion These findings reveal a sex-specific association between serum propionate levels and blood glucose control in women with T1D. Importantly, this relationship appears independent of dietary factors. Trial registration number NCT05936242.

Microbiome composition has been related to blood glucose control in children with type 1 diabetes (T1D). The Mediterranean Diet (MD) influences microbiome composition in healthy people. Whether MD influences blood glucose control in adults with long-lasting T1D through microbiome modification is not known. We aim in this study to investigate the relationships between MD, blood glucose control, and gut microbiome composition in adults with T1D, also exploring the feasibility of using gut microbiome profiles as predictive markers for clinical parameters and dietary patterns. In a cross-sectional study of 253 individuals with T1D, diet was assessed by EPIC questionnaire, adherence to the MD was evaluated by relative Mediterranean diet score (rMED), gut microbiome was analyzed by shotgun metagenomics and glucose control was assessed by HbA1c and continuous glucose monitoring. High adherence to MD was linked to improved blood glucose control, as evidenced by significantly lower HbA1c levels compared to subjects with low adherence. High adherence to MD was significantly associated with enrichment in beneficial microbial species. Conversely, low adherence corresponded to higher levels of potentially harmful species. Microbiome significantly predicted several variables including HbA1c and MD adherence. Our results highlight the beneficial effects of MD adherence on blood glucose control and gut microbiome composition in adults with long-standing T1D. The study was registered at ClinicalTrials.gov with the identifier NCT05936242.

Background: Endothelial dysfunction is recognized as an early modification involved in the pathogenesis of vascular diseases. Evidence suggests that the Mediterranean Diet (MD) is associated with endothelial function improvement and, in turn, plays an important role in atherosclerosis development and progression. Objectives: To evaluate both acute and sustained effects of the MD on endothelial function in patients with high cardiometabolic risk. Methods: A total of 25 subjects were randomly assigned to either the MD group or the Control Diet (CD) group according to a single-blind, parallel-group study design. Endothelial function was evaluated through non-invasive flow-mediated dilation (FMD) measurements at baseline (T0) and after 8 weeks (Tw8) of the MD or CD intervention, under both 12 h fast condition (fasting) and 2 h post-meal resembling the assigned diet (2 h). Assessments were conducted by a blinded sonographer. Results: FMD at T0-fasting was similar between MD and CD groups (6.11% ± 0.67 vs. 7.90% ± 1.65; p = 0.266). A significant difference in FMD between MD and CD groups was observed at T0-2h (12.14% ± 1.93 vs. 4.01% ± 1.03; p = 0.004), T8w-fasting (9.76% ± 1.18 vs. 5.03% ± 0.89; p = 0.008), and T8w-2h (8.99% ± 1.22 vs. 3.86% ± 0.52; p = 0.003). Oral glucose insulin sensitivity (OGIS) at T0 correlated with FMD percent changes from T0-fasting to T0-2h (r = 0.414, p = 0.044). After adjusting for age, gender, and OGIS, MD was an independent predictor of percent changes in FMD from T0-fasting to T0-2h (β: −0.582, p = 0.003), from T0-fasting to T8w-fasting (β: −0.498, p = 0.013), and from T0-fasting to T8w-2h (β: −0.479, p = 0.018). Conclusions: Adherence to the MD may improve endothelial function in both the short- and medium-term among patients at high cardiometabolic risk.