Science Based Nutrition

August 20, 2009

Prevalence of daily hyperglycemia in obese type 2 diabetic men compared with that in lean and obese normoglycemic men: effect of consumption of a sucrose-containing beverage [Carbohydrate metabolism and diabetes]

Background: Hyperglycemia forms a direct and independent risk factor for the development of cardiovascular comorbidities in type 2 diabetes. Consumption of sucrose-sweetened soft drinks might further increase the prevalence of hyperglycemic episodes.

Objective: The objective was to assess glycemic control in type 2 diabetic subjects and healthy lean and obese control subjects under strict dietary standardization but otherwise free-living conditions, with and without the consumption of soft drinks.

Design: Obese type 2 diabetic men (n = 11) and lean (n = 10) and obese (n = 10) normoglycemic male control subjects participated in a randomized crossover study. The subjects were provided with a standardized diet in 2 periods, during which they consumed 250 mL water with or without (control) sucrose (37.5 g) 2 h after breakfast and lunch. Blood glucose concentrations were assessed by continuous glucose monitoring.

Results: In the type 2 diabetic subjects, the mean 24-h glucose concentrations were significantly elevated (9.1 ± 0.6 mmol/L), and hyperglycemia (glucose >10 mmol/L) was evident over 33 ± 8% (8 ± 2 h) of a 24-h period (P < 0.01). Hyperglycemia was rarely present in the normoglycemic lean and obese control subjects (5 ± 2%/24 h for both). Consumption of 75 g sucrose, equivalent to 2 cans of a soft drink, did not further augment the prevalence of hyperglycemia throughout the day in any group.

Conclusions: Type 2 diabetic subjects taking oral blood glucose–lowering medication experience hyperglycemia during most of the daytime. Moderate consumption of sucrose-sweetened beverages does not further increase the prevalence of hyperglycemia in type 2 diabetic subjects or in normoglycemic lean or obese men.

Gluconeogenesis and energy expenditure after a high-protein, carbohydrate-free diet [Energy and protein metabolism]

Background: High-protein diets have been shown to increase energy expenditure (EE).

Objective: The objective was to study whether a high-protein, carbohydrate-free diet (H diet) increases gluconeogenesis and whether this can explain the increase in EE.

Design: Ten healthy men with a mean (±SEM) body mass index (in kg/m2) of 23.0 ± 0.8 and age of 23 ± 1 y received an isoenergetic H diet (H condition; 30%, 0%, and 70% of energy from protein, carbohydrate, and fat, respectively) or a normal-protein diet (N condition; 12%, 55%, and 33% of energy from protein, carbohydrate, and fat, respectively) for 1.5 d according to a randomized crossover design, and EE was measured in a respiration chamber. Endogenous glucose production (EGP) and fractional gluconeogenesis were measured via infusion of [6,6-2H2]glucose and ingestion of 2H2O; absolute gluconeogenesis was calculated by multiplying fractional gluconeogenesis by EGP. Body glycogen stores were lowered at the start of the intervention with an exhaustive glycogen-lowering exercise test.

Results: EGP was lower in the H condition than in the N condition (181 ± 9 compared with 226 ± 9 g/d; P < 0.001), whereas fractional gluconeogenesis was higher (0.95 ± 0.04 compared with 0.64 ± 0.03; P < 0.001) and absolute gluconeogenesis tended to be higher (171 ± 10 compared with 145 ± 10 g/d; P = 0.06) in the H condition than in the N condition. EE (resting metabolic rate) was greater in the H condition than in the N condition (8.46 ± 0.23 compared with 8.12 ± 0.31 MJ/d; P < 0.05). The increase in EE was a function of the increase in gluconeogenesis (EE = 0.007 x gluconeogenesis – 0.038; r = 0.70, R2 = 0.49, P < 0.05). The contribution of gluconeogenesis to EE was 42%; the energy cost of gluconeogenesis was 33% (95% CI: 16%, 50%).

Conclusions: Forty-two percent of the increase in energy expenditure after the H diet was explained by the increase in gluconeogenesis. The cost of gluconeogenesis was 33% of the energy content of the produced glucose.

June 19, 2009

[Carbohydrate metabolism and diabetes] Dairy and industrial sources of trans fat do not impair peripheral insulin sensitivity in overweight women

Filed under: Main Content — Tags: , , , , , , , , , , , , , , , , , , , , , , , — Tardy, A.-L., Lambert-Porcheron, S., Malpuech-Brugere, C., Giraudet, C., Rigaudiere, J.-P., Laillet, B., LeRuyet, P., Peyraud, J.-L., Boirie, Y., Laville, M., Michalski, M.-C., Chardigny, J.-M., Morio, B. @ 5:00 am

Background: The 2 major dietary sources of trans fatty acids (TFAs) are partially hydrogenated oils and ruminant-derived products. Epidemiologic data suggest that chronic consumption of industrial sources of TFAs could be damaging to insulin sensitivity, but intervention studies on this issue have remained inconclusive.

Objective: The trial was designed to compare the effects of dairy compared with industrial sources of TFAs on insulin sensitivity in overweight women.

Design: Sixty-three healthy women with abdominal obesity [waist circumference >88 cm and a body mass index (in kg/m2) >28] were recruited. After a run-in period, the volunteers were randomly assigned to consume 1 of 3 four-week diets: 60 g low-TFA lipids/d (0.54 g/d; n = 21), ruminant TFA–rich lipids (4.86 g/d; n = 21), or industrial TFA–rich lipids (5.58 g/d; n = 21). Changes in peripheral insulin sensitivity were assessed by using hyperinsulinemic-euglycemic clamps.

Results: After the intervention period, fasting glycemia and insulinemia and insulin sensitivity were not significantly modified in either group (P > 0.05).

Conclusions: These data indicate that consumption of dairy- and industrial-source TFAs for 4 wk at nutritional levels do not impair peripheral insulin sensitivity in insulin-resistant women. Our study may not preassess the effects of TFAs in normal insulin-sensitive individuals. This trial was registered at clinicaltrials.gov as NCT00617435.

May 20, 2009

[Carbohydrate metabolism and diabetes] Fructose overconsumption causes dyslipidemia and ectopic lipid deposition in healthy subjects with and without a family history of type 2 diabetes

Background: Both nutritional and genetic factors are involved in the pathogenesis of nonalcoholic fatty liver disease and insulin resistance.

Objective: The aim was to assess the effects of fructose, a potent stimulator of hepatic de novo lipogenesis, on intrahepatocellular lipids (IHCLs) and insulin sensitivity in healthy offspring of patients with type 2 diabetes (OffT2D)—a subgroup of individuals prone to metabolic disorders.

Design: Sixteen male OffT2D and 8 control subjects were studied in a crossover design after either a 7-d isocaloric diet or a hypercaloric high-fructose diet (3.5 g · kg FFM–1 · d–1, +35% energy intake). Hepatic and whole-body insulin sensitivity were assessed with a 2-step hyperinsulinemic euglycemic clamp (0.3 and 1.0 mU · kg–1 · min–1), together with 6,6-[2H2]glucose. IHCLs and intramyocellular lipids (IMCLs) were measured by 1H-magnetic resonance spectroscopy.

Results: The OffT2D group had significantly (P < 0.05) higher IHCLs (+94%), total triacylglycerols (+35%), and lower whole-body insulin sensitivity (–27%) than did the control group. The high-fructose diet significantly increased IHCLs (control: +76%; OffT2D: +79%), IMCLs (control: +47%; OffT2D: +24%), VLDL-triacylglycerols (control: +51%; OffT2D: +110%), and fasting hepatic glucose output (control: +4%; OffT2D: +5%). Furthermore, the effects of fructose on VLDL-triacylglycerols were higher in the OffT2D group (group x diet interaction: P < 0.05).

Conclusions: A 7-d high-fructose diet increased ectopic lipid deposition in liver and muscle and fasting VLDL-triacylglycerols and decreased hepatic insulin sensitivity. Fructose-induced alterations in VLDL-triacylglycerols appeared to be of greater magnitude in the OffT2D group, which suggests that these individuals may be more prone to developing dyslipidemia when challenged by high fructose intakes. This trial was registered at clinicaltrials.gov as NCT00523562.

September 1, 2006

An extract of black, green, and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers

Filed under: Main Content — Tags: , , , , , , — Litao Zhong, Julie K Furne, Michael D Levitt @ 9:00 am
Litao Zhong, Julie K Furne, Michael D Levitt
Sep 1, 2006; 84:551-555
Carbohydrate metabolism and diabetes
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