Effect of ethnicity on glycaemic index: a systematic review and meta-analysis

The effect of adding protein to a carbohydrate meal on postprandial glucose and insulin responses: a systematic review and meta-analysis of acute controlled feeding trials

BACKGROUND

protein influences acute postprandial-glucose and -insulin responses but the effects of dose, protein-type and health-status are unknown.

OBJECTIVE

to determine the acute effect of adding protein to carbohydrate on postprandial responses and identify effect modifiers.

METHODS

we searched MEDLINE, EMBASE and Cochrane databases through 30 July 2023 for acute, crossover trials comparing acute postprandial-responses elicited by carbohydrate-containing test-meals with vs without added protein in adults without-diabetes or with type-2 (T2DM) or type-1 (T1DM) diabetes. Group data were pooled separately using generic inverse-variance with random-effects models and expressed as ratio-of-means with [95% CIs]. Risk-of-bias and certainty-of-evidence (GRADE) were assessed.

RESULTS

in 154 trial-comparisons of animal-, dairy- and plant-proteins (without-diabetes, n=22,67,32; T2DM, n=14,16,3), each gram-protein/gram-carbohydrate (g/g) reduced glucose-area-under-the-curve (AUC) less in T2DM than in those without-diabetes (-10% vs -50%, P<0.05) but increased insulin-AUC similarly (+76 vs +56%, respectively). In subjects without-diabetes, each g/g of dairy- and plant-proteins reduced glucose-AUC by 52 and 55% and increased insulin-AUC by 64 and 45% (all P<0.05). Animal-proteins significantly reduced glucose-AUC by 31% and increased insulin-AUC by 37% (pooled effects), but without a significant dose-response. In T2DM animal-protein reduced glucose-AUC by 13% and increased insulin-AUC by 105%, with no significant dose-response. Dairy-protein reduced glucose-AUC by 18% (no dose-response), but each g/g increased insulin-AUC by 34% (P<0.05). In T1DM protein increased glucose-AUC by 40% (P<0.05, n=5). Data-source (reported vs calculated) and study-methodology-quality significantly modified some outcomes and contributed to high between-study heterogeneity.

CONCLUSIONS

in people without-diabetes, adding dairy- or plant-protein to a carbohydrate-containing meal elicits physiologically significant reductions in glucose-AUC and increases insulin-AUC. Animal-protein may slightly reduce glucose-AUC and may increase insulin-AUC. In T2DM, protein may not have such large and consistent effects. Further research is needed to determine if the effects of protein differ by health status and protein-source.

REGISTRATION

PROSPERO CRD42022322090.

FUNDING

General Mills.

Ethnic Variability in Glucose and Insulin Response to Rice Among Healthy Overweight Adults: A Randomized Cross-Over Study

BACKGROUND

The influence of ethnicity on postprandial glucose and insulin responses has been reported earlier and rice is a major contributor to the overall glycaemic load of Asian and Arab diets. This study aims to compare postprandial glycaemic and insulinaemic responses to rice among healthy overweight Asian, Arab and European participants.

METHODS

In a randomized crossover design, 47 healthy overweight participants (23 Asian, 16 Arab, and 8 European) consumed 75 grams of glucose beverage or ate 270 grams of cooked basmati rice (75 g of available carbohydrate) on two separate occasions, separated by a one 1-week washout period. Blood glucose and insulin levels were determined at fasting 0 (fasting), 30, 60, and 120 minutes and used to determine the incremental area under the curve (iAUC).

RESULTS

The three groups were matched on body mass index and gender. Although no differences were noted statistically in most clinical features, a wide range of variation was noted in age, systolic, diastolic blood pressure. The fasting blood glucose and insulin levels were highest among Asians, followed by Arabs and Europeans (p < 0.01). According to the HOMA-IR test and the Matsuda index, Asians have a higher insulin resistance than Arabs or Europeans when consuming a glucose beverage (p < 0.001) and rice (p < 0.01). Postprandial glucose and insulin responses to glucose beverage did not differ between ethnic groups (p = 0.28; p = 0.10). Based on an unadjusted regression model, European participants had significantly lower iAUC-glucose (p = 0.02) and iAUC-insulin (p = 0.01) after rice consumption than Asian participants. In the adjusted model, the difference between the two groups remained for iAUC-insulin (p = 0.04) but not for iAUC-glucose (p = 0.07).

CONCLUSION

Our study found that ethnic differences exist among healthy overweight adults in terms of insulin resistance, glycaemic response and insulinaemic response to rice. As a result of their high insulin resistance, Asian participants had a higher postprandial insulin spike than Europeans after eating rice. These findings could have substantial implications for nutrition recommendations based on ethnicity, particularly for Asians.

Ethnicity impact on oral processing behaviour and glycemic response to noodles: Chinese (Asian) vs. New Zealander (Caucasian)

There is an increasing awareness of the link between food breakdown during chewing and its nutrient release and absorption in the gastrointestinal tract. However, how oral processing behaviour varies among different ethnic groups, and how such difference further impacts on bolus characteristics and consequently glycemic response (GR) are not well understood. In this study, we recruited a group of Asian (Chinese) subjects in China (n = 32) and a group of Caucasian subjects in New Zealand (n = 30), both aged between 18 and 30 years, and compared their blood glucose level (BGL) over 120 min following consumption of a glucose drink and cooked white noodles. We also assessed their chewing behaviour, unstimulated saliva flow rate, and ready-to-swallow bolus characteristics to determine whether these measures explain the ethnic differences in postprandial glycaemia. Compared to New Zealand subjects, the Chinese subjects showed 35% slower saliva flow rate but around 2 times higher salivary α-amylase activity in the unstimulated state. During consumption of noodles, Chinese subjects on average took a larger mouthful size, chewed each mouthful for longer and swallowed a larger number of particles with a smaller particle size area. Total GR measured by area under the curve (IAUC) was higher among the Chinese subjects. They also experienced higher BGL at 15 min, as well as higher peak BGL. There were strong correlations observed between oral processing and GR parameters. Results of this study confirmed the significance of oral processing in determining food digestion, and will provide new insights on the role of ethnicity in influencing people's physiological response to food.

Decreasing the RAG:SAG ratio of granola cereal predictably reduces postprandial glucose and insulin responses: a report of four randomised trials in healthy adults

Dietary starch contains rapidly (RAG) and slowly available glucose (SAG). To establish the relationships between the RAG:SAG ratio and postprandial glucose, insulin and hunger, we measured postprandial responses elicited by test meals varying in the RAG:SAG ratio in n 160 healthy adults, each of whom participated in one of four randomised cross-over studies (n 40 each): a pilot trial comparing six chews (RAG:SAG ratio 2·4–42·7) and three studies comparing a test granola (TG1-3, RAG:SAG ratio 4·5–5·2) with a control granola (CG1–3, RAG:SAG ratio 54·8–69·3). Within studies, test meals were matched for fat, protein and available carbohydrate. Blood glucose, serum insulin and subjective hunger were measured for 3 h. Data were subjected to repeated-measures analysis of variance (ANOVA). The relationships between the RAG:SAG ratio and postprandial end points were determined by regression analysis. In the pilot trial, 0–2 h glucose incremental areas under the curve (iAUC0–2; primary end point) varied across the six chews (P = 0·014) with each 50 % reduction in the RAG:SAG ratio reducing relative glucose response by 4·0 %. TGs1-3 elicited significantly lower glucose iAUC0–2 than CGs1–3 by 17, 18 and 17 %, respectively (similar to the 15 % reduction predicted by the pilot trial). The combined means ± sem (n 120) for TC and CG were glucose iAUC0–2, 98 ± 4 v. 118 ± 4 mmol × min/l (P < 0·001), and insulin iAUC0–2, 153 ± 9 v. 184 ± 11 nmol × h/l (P < 0·001), respectively. Neither postprandial hunger nor glucose or hunger increments 2 h after eating differed significantly between TG and CG. We concluded that TGs with RAG:SAG ratios <5·5 predictably reduced glycaemic and insulinaemic responses compared with CGs with RAG:SAG ratios >54. However, compared with CG, TG did not reduce postprandial hunger or delay the return of glucose or hunger to baseline.

Raman Fingerprints of Rice Nutritional Quality: A Comparison between Japanese Koshihikari and Internationally Renowned Cultivars

Raman spectroscopy was applied to characterize at the molecular scale the nutritional quality of the Japanese Koshihikari rice cultivar in comparison with other renowned rice cultivars including Carnaroli from Italy, Calrose from the USA, Jasmine rice from Thailand, and Basmati from both India and Pakistan. For comparison, two glutinous (mochigome) cultivars were also investigated. Calibrated and validated Raman analytical algorithms allowed quantitative determinations of: (i) amylopectin and amylose concentrations, (ii) fractions of aromatic amino acids, and (iii) protein content and secondary structure. The Raman assessments non-destructively linked the molecular composition of grains to key nutritional parameters and revealed a complex intertwine of chemical properties. The Koshihikari cultivar was rich in proteins (but with low statistical relevance as compared to other investigated cultivars) and aromatic amino acids. However, it also induced a clearly higher glycemic impact as compared to long-grain cultivars from Asian countries. Complementary to genomics and wet-chemistry analyses, Raman spectroscopy makes non-destructively available factual and data-driven information on rice nutritional characteristics, thus providing customers, dietitian nutritionists, and producers with a solid science-consolidated platform.

Raman spectroscopic analysis of polysaccharides in popular Japanese rice cultivars

Analytical algorithms based on Raman spectroscopy are proposed for the determination of amylopectin and amylose concentrations in polished white rice, and applied to characterize and compare linear and branched polysaccharide structures in nine different types of Japanese rice. A selected algorithm used symmetric bending vibrations of the COC glycosidic linkage from a relatively narrow spectral zone between 830 and 895 cm^-1. It specifically compared the intensity of Raman signals from two types of bending common to both starch components (C1-O-C5 and C1-O-C4 at 868 and 855 cm^-1, respectively) and that at the branch point peculiar to amylopectin (C1-O-C6 at 844 cm^-1). Raman data were confronted with data collected by conventional amylose-iodine colorimetry method. Consistency was found between Raman and colorimetric methods over the entire series of tested rice cultivars, thus validating the newly proposed spectroscopic algorithm. The amylose content of the tested rice species broadly varied between 1.2 and 20.4%. The proposed Raman algorithm allows fast and nondestructive determination of amylose content in rice with minimal sample preparation. These characteristics might be key in the development of portable Raman devices capable to promptly screen polysaccharides in different rice cultivars with respect to their interannual and plantation-related fluctuations.

The effect of oat β-glucan on postprandial blood glucose and insulin responses: a systematic review and meta-analysis

To determine the effect of oat β‑glucan (OBG) on acute glucose and insulin responses and identify significant effect modifiers we searched the MEDLINE, EMBASE, and Cochrane databases through October 27, 2020 for acute, crossover, controlled feeding trials investigating the effect of adding OBG (concentrate or oat-bran) to carbohydrate-containing test-meals compared to comparable or different carbohydrate-matched control-meals in humans regardless of health status. The primary outcome was glucose incremental area-under-the-curve (iAUC). Secondary outcomes were insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two reviewers extracted the data and assessed risk-of-bias and certainty-of-evidence (GRADE). Data were pooled using generic inverse-variance with random-effects model and expressed as ratio-of-means with [95% CIs]. We included 103 trial comparisons (N = 538). OBG reduced glucose iAUC and iPeak by 23% (0.77 [0.74, 0.81]) and 28% (0.72 [0.64, 0.76]) and insulin by 22% (0.78 [0.72, 0.85]) and 24% (0.76 [0.65, 0.88]), respectively. Dose, molecular-weight, and comparator were significant effect modifiers of glucose iAUC and iPeak. Significant linear dose-response relationships were observed for all outcomes. OBG molecular-weight >300 kg/mol significantly reduced glucose iAUC and iPeak, whereas molecular-weight <300 kg/mol did not. Reductions in glucose iAUC (27 vs 20%, p = 0.03) and iPeak (39 vs 25%, p < 0.01) were significantly larger with different vs comparable control-meals. Outcomes were similar in participants with and without diabetes. All outcomes had high certainty-of-evidence. In conclusion, current evidence indicates that adding OBG to carbohydrate-containing meals reduces glycaemic and insulinaemic responses. However, the magnitude of glucose reduction depends on OBG dose, molecular-weight, and the comparator.

Discharge pharmacotherapy for Type 2 diabetic inpatients at two hospitals of different tiers in Zhejiang Province, China

Objects

To look into the discharge pharmacotherapy for type 2 diabetics admitted to two general hospitals of different ranks and inspect current real-world management of discharge pharmacology and its related factors.

Methods

Type 2 diabetics admitted to a tertiary general hospital (Ningbo Medical Treatment Centre Lihuili Hospital, LHLH) or a secondary general hospital (Simen Hospital, SMH) for intensification of their anti-diabetics were included for retrospective analysis. Patients’ demographics, clinical characteristics, admission diabetes therapy and discharge diabetes pharmacology were analyzed and compared among patients in each hospital as well as between two hospitals.

Results

391 patients from LHLH and 164 patients from SMH were included for analyzing. Compared with patients from LHLH, patients from SMH were older, more illiterate and had higher HbA1c concentrations. While there was a nearly equal split of oral anti-diabetes drugs (OADs)-only and Insulin treatment in LHLH’s discharge pharmacotherapy, insulin treatment dominated SMH’s. Basal-and-bolus insulin assumed the majority of SMH’s insulin regimens but only accounted for less than 20% of LHLH’s. The principal discrepancy in OADs-only treatment existed in the utilization of newer classes of OADs. Cost and body mass index (BMI) were the main differentiating factors among OADs-only treatments while duration, BMI and HbA1c differ among insulin treatments at LHLH. Clinical characteristics didn’t significantly differ among OADs-only treatments and HbA1c was the only differentiating factor among insulin treatments at SMH. Overall, hospital, duration, HbA1c, and vascular diseases were main factors that affect discharge pharmacology.

Conclusions

Great disparities exist in the discharge pharmacotherapy at two hospitals. Diabetes management is mostly glucose-oriented at SMH while multifactorial considerations were reflected in LHLH’s discharge pharmacotherapy. Besides differences in patients’ demographics, medication availability and diagnosis of early-stage vascular complications, lack of practical algorithm for discharge management in T2DM may be the underlying deficiency and a key part for future improvement.

Glycemic Index and Insulinemic Index of Foods: An Interlaboratory Study Using the ISO 2010 Method

An official method for determining food glycemic index (GI) was published by the Organization for International Standardization (ISO) in 2010, but its performance has not been assessed. Therefore, we aimed to determine the intra- and inter-laboratory variation of food GI values measured using the 2010 ISO method. Three laboratories (Australia, Canada and France) determined the GI and insulinemic-index (II) of six foods in groups of 13–15 participants using the 2010 ISO method and intra- and inter-laboratory Standard Deviations (SDs) were calculated. Overall mean food GIs varied from 47 to 86 (p < 0.0001) with no significant difference among labs (p = 0.57) and no food × laboratory interaction (p = 0.20). Within-laboratory SD was similar among foods (range, 17.8–22.5; p = 0.49) but varied among laboratories (range 17.5–23.1; p = 0.047). Between-laboratory SD of mean food GI values ranged from 1.6 to 6.7 (mean, 5.1). Mean glucose and insulin responses varied among foods (p < 0.001) with insulin (p = 0.0037), but not glucose (p = 0.054), varying significantly among labs. Mean II varied among foods (p < 0.001) but not among labs (p = 0.94). In conclusion, we found that using the 2010 ISO method, the mean between-laboratory SD of GI was 5.1. This suggests that the ISO method is sufficiently precise to distinguish a mean GI = 55 from a mean GI ≥ 70 with 97–99% probability.

Comparison of a twice daily injection of insulin aspart 50 with insulin aspart 30 in patients with poorly controlled type 2 diabetes

OBJECTIVE

To compare the efficacy and safety of a twice daily injection of insulin aspart (BIAsp) 30 and BIAsp50 in patients with type 2 diabetes mellitus (T2DM) poorly controlled with oral hypoglycemic agents (OHAs).

METHODS

In this 12 week prospective, randomized, parallel trial, a total of 80 T2DM patients, 59 ± 10 years old with a disease duration of 9.3 ± 6.6 years and HbA1c >7% despite large doses of metformin and sulfonylurea administration, were randomized to receive BIAsp30 (n = 40) or BIAsp50 (n = 40). The primary endpoint was a change in HbA1c at week 12.

RESULTS

The changes in HbA1c from baseline were -2.5% ± 1.0% in the BIAsp50 group and -2.5% ± 1.2% in the BIAsp30 group (p = .897). No difference was observed in the rate of HbA1c target achievement (<7.0%) between BIAsp50 (42.5%) and BIAsp30 (32.5%) (p = .495). The change in fasting plasma glucose (FPG) in the BIAsp50 group was lower than that in the BIAsp30 group (p < .001), while the change in two-hour postprandial blood glucose (2hPBG) was higher and blood glucose excursion was lower in the BIAsp50 group than that in the BIAsp30 group (p < .001, p < .001). A significant improvement in HbA1c was observed with BIAsp50 in subgroups with baseline blood glucose excursion >7.8 mmol/L or 2hPBG >17.6 mmol/L compared with BIAsp30. There were no differences in hypoglycemia or body weight between groups.

CONCLUSIONS

Compared with BIAsp30, BIAsp50 showed greater efficacy in patients with baseline BG excursion >7.8 mmol/L or 2hPBG >17.6 mmol/L as well as good safety for hypoglycemia.

CLINICAL TRIAL REGISTRATION

ChiCTR-IIR-16008958.

Comparison of insulin lispro mix 25 with insulin lispro mix 50 as insulin starter in Chinese patients with type 2 diabetes mellitus (CLASSIFY study): Subgroup analysis of a Phase 4 open-label randomized trial

BACKGROUND

Premixed insulins are recommended starter insulins in Chinese patients after oral antihyperglycemic medication (OAM) failure. In the present study, we compared the efficacy and safety of insulin lispro mix 25 (LM25) twice daily (b.i.d.) and insulin lispro mix 50 (LM50) b.i.d. as a starter insulin regimen in Chinese patients with type 2 diabetes mellitus (T2DM) who had inadequate glycemic control with OAMs.

METHODS

The primary efficacy outcome in the present open-label parallel randomized clinical trial was change in HbA1c from baseline to 26 weeks. Patients were randomized in a ratio of 1:  1 to LM25 (n = 80) or LM50 (n = 76). A mixed-effects model with repeated measures was used to analyze continuous variables. The Cochran-Mantel-Haenszel test with stratification factor was used to analyze categorical variables.

RESULTS

At the end of the study, LM50 was more efficacious than LM25 in reducing mean HbA1c levels (least-squares [LS] mean difference 0.48; 95 % confidence interval [CI] 0.22, 0.74; P < 0.001). More subjects in the LM50 than LM25 group achieved HbA1c targets of <7.0 % (72.4 % vs 45.0 %; P = 0.001) or ≤6.5 % (52.6 % vs 20.0 %; P < 0.001). Furthermore, LM50 was more effective than LM25 at reducing HbA1c in patients with baseline HbA1c, blood glucose excursion, and postprandial glucose greater than or equal to median levels (P ≤ 0.001). The rate and incidence of hypoglycemic episodes and increase in weight at the end of the study were similar between treatment groups.

CONCLUSIONS

In Chinese patients with T2DM, LM50 was more efficacious than LM25 as a starter insulin.