Dietary Management of Type 2 Diabetes: A Personal Odyssey

Multiplatform metabolomics for an integrative exploration of metabolic syndrome in older men

BACKGROUND

Metabolic syndrome (MetS), a cluster of factors associated with risks of developing cardiovascular diseases, is a public health concern because of its growing prevalence. Considering the combination of concomitant components, their development and severity, MetS phenotypes are largely heterogeneous, inducing disparity in diagnosis.

METHODS

A case/control study was designed within the NuAge longitudinal cohort on aging. From a 3-year follow-up of 123 stable individuals, we present a deep phenotyping approach based on a multiplatform metabolomics and lipidomics untargeted strategy to better characterize metabolic perturbations in MetS and define a comprehensive MetS signature stable over time in older men.

FINDINGS

We characterize significant changes associated with MetS, involving modulations of 476 metabolites and lipids, and representing 16% of the detected serum metabolome/lipidome. These results revealed a systemic alteration of metabolism, involving various metabolic pathways (urea cycle, amino-acid, sphingo- and glycerophospholipid, and sugar metabolisms…) not only intrinsically interrelated, but also reflecting environmental factors (nutrition, microbiota, physical activity…).

INTERPRETATION

These findings allowed identifying a comprehensive MetS signature, reduced to 26 metabolites for future translation into clinical applications for better diagnosing MetS.

FUNDING

The NuAge Study was supported by a research grant from the Canadian Institutes of Health Research (CIHR; MOP-62842). The actual NuAge Database and Biobank, containing data and biologic samples of 1,753 NuAge participants (from the initial 1,793 participants), are supported by the Fonds de recherche du Québec (FRQ; 2020-VICO-279753), the Quebec Network for Research on Aging, a thematic network funded by the Fonds de Recherche du Québec - Santé (FRQS) and by the Merck-Frost Chair funded by La Fondation de l'Université de Sherbrooke. All metabolomics and lipidomics analyses were funded and performed within the metaboHUB French infrastructure (ANR-INBS-0010). All authors had full access to the full data in the study and accept responsibility to submit for publication.

The Importance of Lactose in the Human Diet: Outcomes of a Mexican Consensus Meeting

Lactose is a unique component of breast milk, many infant formulas and dairy products, and is widely used in pharmaceutical products. In spite of that, its role in human nutrition or lactose intolerance is generally not well-understood. For that reason, a 2-day-long lactose consensus meeting with health care professionals was organized in Mexico to come to a set of statements for which consensus could be gathered. Topics ranging from lactase expression to potential health benefits of lactose were introduced by experts, and that was followed by a discussion on concept statements. Interestingly, lactose does not seem to induce a neurological reward response when consumed. Although lactose digestion is optimal, it supplies galactose for liver glycogen synthesis. In infants, it cannot be ignored that lactose-derived galactose is needed for the synthesis of glycosylated macromolecules. At least beyond infancy, the low glycemic index of lactose might be metabolically beneficial. When lactase expression decreases, lactose maldigestion may lead to lactose intolerance symptoms. In infancy, the temporary replacing of lactose by other carbohydrates is only justified in case of severe intolerance symptoms. In those who show an (epi)genetic decrease or absence of lactase expression, a certain amount (for adults mostly up to 12 g per portion) of lactose can still be consumed. In these cases, lactose shows beneficial intestinal-microbiota-shaping effects. Avoiding lactose-containing products may imply a lower intake of other important nutrients, such as calcium and vitamin B12 from dairy products, as well as an increased intake of less beneficial carbohydrates.

Low Starch/Low Dairy Diet Results in Successful Treatment of Obesity and Co-Morbidities Linked to Polycystic Ovary Syndrome (PCOS)

Background

Polycystic Ovary Syndrome (PCOS) affects approximately 15% of reproductive-age women and increases risk of insulin resistance, type 2 diabetes mellitus, cardiovascular disease, cancer and infertility. Hyperinsulinemia is believed to contribute to or worsen all of these conditions, and increases androgens in women with PCOS. Carbohydrates are the main stimulators of insulin release, but research shows that dairy products and starches elicit greater postprandial insulin secretion than non-starchy vegetables and fruits. The purpose of this study was to determine whether an 8-week low-starch/low-dairy diet results in weight loss, increased insulin sensitivity, and reduced testosterone in women with PCOS.

Methods

Prospective 8-week dietary intervention using an ad libitum low starch/low dairy diet in 24 overweight and obese women (BMI ≥ 25 kg/m² and ≤ 45 kg/m²) with PCOS. Diagnosis of PCOS was based on the Rotterdam criteria. Weight, BMI, Waist Circumference (WC), Waist-to-Height Ratio (WHtR), fasting and 2-hour glucose and insulin, homeostasis model assessment of Insulin Resistance (HOMA-IR), HbA1c, total and free testosterone, and Ferriman-Gallwey scores were measured before and after the 8-week intervention.

Results

There was a reduction in weight (−8.61 ± 2.34 kg, p<0.001), BMI (−3.25 ± 0.88 kg/m², p<0.001), WC (−8.4 ± 3.1 cm, p<0.001), WHtR (−0.05 ± 0.02 inches, p<0.001), fasting insulin (−17.0 ± 13.6 μg/mL, p<0.001) and 2-hour insulin (−82.8 ± 177.7 μg/mL, p=0.03), and HOMA-IR (−1.9 ± 1.2, p<0.001) after diet intervention. Total testosterone (−10.0 ± 17.0 ng/dL, p=0.008), free testosterone (−1.8 pg/dL, p=0.043) and Ferriman-Gallwey scores (−2.1 ± 2.7 points (p=0.001) were also reduced from pre- to post-intervention.

Conclusion

An 8-week low-starch/low-dairy diet resulted in weight loss, improved insulin sensitivity and reduced testosterone in women with PCOS.

Effect of a low-starch/low-dairy diet on fat oxidation in overweight and obese women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects between 4%-18% of reproductive-aged women and is associated with increased risk of obesity and obesity-related disease. PCOS is associated with hyperinsulinemia, which is known to impair fat oxidation. Research shows that carbohydrates from dairy and starch-based foods cause greater postprandial insulin secretion than carbohydrates from nonstarchy vegetables and fruits. The purpose of this study was to determine whether an ad libitum 8-week low-starch/low-dairy diet would improve fasting and postprandial fat oxidation after a high saturated fat liquid meal (HSFLM) in overweight and obese women with PCOS. Prospective 8-week dietary intervention using a low-starch/low-dairy diet in 10 women (body mass index ≥25 kg/m(2) and ≤45 kg/m(2)) with PCOS. Indirect calorimetry was used at fasting and for 5 h following consumption of the HSFLM to determine respiratory exchange ratio (RER), macronutrient oxidation, and energy expenditure (EE) at week 0 and week 8. Participants had a reduction in body weight (-8.1 ± 1.8 kg, p < 0.05) and fasting insulin (-19.5 ± 8.9 μg/mL, p < 0.05) after dietary intervention; however, these were not significantly correlated with improved fat oxidation. There was a reduction in fasting RER, and fasting and postprandial carbohydrate oxidation, and an increase in fasting and postprandial fat oxidation after adjusting for body weight. There was also significant difference in incremental area under the curve from pre- to post-diet for fat (0.06 ± 0.00 g/kg per 5 h; p < 0.001) and carbohydrate oxidation (-0.29 ± 0.06 g/kg per 5 h; p < 0.001), but not for RER or EE. In conclusion, an 8-week low-starch/low-dairy diet increased fat oxidation in overweight and obese women with PCOS.

Protein co-ingestion strongly increases postprandial insulin secretion in type 2 diabetes patients

The capacity of nutritional protein to induce endogenous insulin secretion has been well established. However, it is not known whether such a response is applicable in a diverse population of type 2 diabetes patients. The aim of the present study was to assess the impact of co-ingesting either intact or hydrolyzed protein with carbohydrate on postprandial plasma insulin and glucose responses in type 2 diabetes patients. Sixty longstanding, male, type 2 diabetes patients participated in a study in which we determined postprandial plasma insulin and glucose responses after ingesting a single bolus of carbohydrate (0.7 g/kg: CHO) with or without an intact protein (0.3 g/kg: PRO) or its hydrolysate (0.3 g/kg: PROh). Results showed that protein co-ingestion strongly increased postprandial insulin release, with the insulin response +99 ± 41 and +110 ± 10% greater in the CHO+PRO and CHO+PROh experiments when compared with the CHO experiment. The insulinotropic properties of protein co-ingestion were evident in nearly all patients, with 58 out of 60 patients responding >10% when compared with the insulin response following carbohydrate ingestion only (CHO). The concomitant plasma glucose responses were 22 ± 32 and 23 ± 36% lower in the CHO+PRO and CHO+PROh experiments, respectively. We conclude that protein co-ingestion represents an effective dietary strategy to strongly augment postprandial insulin release and attenuate the postprandial rise in glucose concentration in type 2 diabetes patients.

Traditional dietary recommendations for the prevention of cardiovascular disease: do they meet the needs of our patients?

The characteristics of patients with CVD have changed: whereas smoking prevalence declines, obesity and metabolic syndrome are on the rise. Unfortunately, the traditional low-fat diet for the prevention of cardiovascular disease (CVD) still seems to be the “mainstream knowledge” despite contradicting evidence. But lowering LDL-cholesterol by the wrong diet even may be counterproductive, if sd-LDL is raised and HDL is lowered. New insights into the pathophysiology of insulin resistance and its influence on the effects of dietary changes have led to a better approach: (1) the higher a patient's insulin resistance, the more important is the glycemic load of the diet. (2) Fat quality is much more important than fat quantity. (3) The best principle for a reduced calorie intake is not fat counting, but a high volume diet with low energy density, which means fibre rich vegetables and fruits. (4) And finally, satiation and palatability of a diet is very important: there is no success without the patient's compliance. Thus, the best approach to the dietary prevention of CVD is a Mediterranean style low-carb diet represented in the LOGI pyramid. Dietary guidelines for the prevention of CVD should to be revised accordingly.