Effect of insulin and energy restriction on the thermic effect of protein in type 2 diabetes mellitus

Postprandial hyperaminoacidaemia overcomes insulin resistance of protein anabolism in men with type 2 diabetes

AIMS/HYPOTHESIS

Although protein is usually ignored when considering insulin resistance, we have shown resistance of protein concurrent with glucose metabolism in men with type 2 diabetes during a hyperinsulinaemic clamp at euglycaemia and fasting aminoacidaemia. We hypothesised that this resistance is even worse during conditions that simulate the postprandial state, when anabolism should be maximal.

METHODS

Eight overweight and obese men with type 2 diabetes underwent a hyperinsulinaemic-hyperglycaemic (8 mmol/l) clamp, first with plasma amino acids at postabsorptive (Hyper-2) then at postprandial concentrations (Hyper-3). Whole-body protein kinetics were assessed using L-: [1-(13)C]leucine. Hyper-2 results were compared with those of diabetic men whose plasma glucose was lowered to 5.5 mmol/l and fasting aminoacidaemia maintained during the hyperinsulinaemic clamp (Hyper-1).

RESULTS

In Hyper-2 vs Hyper-1 clamps, leucine flux (2.99 ± 0.16 vs 2.62 ± 0.06 μmol kg [fat-free mass (FFM)](-1) min(-1)), rates of synthesis (2.31 ± 0.15 vs 1.98 ± 0.06) and breakdown (2.38 ± 0.16 vs 2.00 ± 0.07) were higher (p < 0.05), but leucine oxidation and net balance did not differ. In Hyper-3 vs Hyper-2 clamps, leucine flux and synthesis and oxidation rates increased markedly as did net balance (0.84 ± 0.09 vs -0.07 ± 0.04 μmol [kg FFM](-1) min(-1), p < 0.0001).

CONCLUSIONS/INTERPRETATION

In type 2 diabetic men, insulin resistance of protein metabolism is of the same magnitude at 8 vs 5.5 mmol/l, but turnover rates are higher with hyperglycaemia. Contrary to our hypothesis, sustained postprandial-level hyperaminoacidaemia stimulated positive net protein balance comparable with that previously found in lean non-diabetic men. This was sufficient to overcome the insulin resistance of protein anabolism.

Moderate-carbohydrate low-fat versus low-carbohydrate high-fat meal replacements for weight loss

OBJECTIVES

To compare the efficacy of a low-carbohydrate high-fat versus a moderate-carbohydrate low-fat diet for weight loss and cardiovascular risk reduction.

METHODS

In a prospective clinical trial, 137 participants (body mass index >or=25 kg/m2) were randomly assigned to Control (46 randomized, 44 completed), Low Carbohydrate (45 randomized, 42 completed), or Moderate Carbohydrate (46 randomized, 40 completed) groups. Outcomes included measures of body size and composition and blood chemistries.

RESULTS

Both the Low and Moderate Carbohydrate groups lost significantly more weight as well as inches from their waists and thighs than the Control group, while the Low Carbohydrate group lost a greater percentage of body fat. Although the Moderate Carbohydrate group showed significant reductions in serum cholesterol, the Low Carbohydrate group showed the greatest improvements in serum cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and very-low-density lipoprotein.

CONCLUSIONS

Moderate approaches to weight loss such as a moderate-carbohydrate low-fat diet may be prudent.

Ready-to-eat cereal products as meal replacements for weight loss

OBJECTIVE

To test the effectiveness of three commercially available partial meal replacement products on weight-loss outcomes.

METHODS

In a randomized controlled clinical trial, 164 eligible overweight and obese adults (ages 18-65 years; body mass index >/=25 kg/m(2)) were randomly assigned to a Control group (CN) or to one of three intervention groups, including 'Cereal Substitution plus Nutrient Bar' (CB), 'Cereal and Waffle Substitution plus Nutrient Bar' (CWB), and 'Cereal Substitution, no Nutrient Bar' (CR).

RESULTS

Compared with the CN group, the CB, CWB, and CR groups evidenced significantly greater reductions in weight, body mass index, waist, hip, and thigh measurements, and the CB and CR groups evidenced significantly greater reductions in percentage body fat. Despite strong adherence (88%) and retention (80%), the groups did not differ in cardiovascular risk profile, mood, or satiety.

CONCLUSIONS

A variety of ready-to-eat cereal products may be safely and effectively used as meal replacements in weight-loss programs.

The prediction of resting energy expenditure in type 2 diabetes mellitus is improved by factoring for glycemia

BACKGROUND

Predictive equations have been reported to overestimate resting energy expenditure (REE) for obese persons. The presence of hyperglycemia results in elevated REE in obese persons with type 2 diabetes, and its effect on the validity of these equations is unknown.

OBJECTIVE

We tested whether (1) indicators of diabetes control were independent associates of REE in type 2 diabetes and (2) their inclusion would improve predictive equations.

DESIGN

A cross-sectional study of 65 (25 men, 40 women) obese type 2 diabetic subjects. Variables measured were: REE by ventilated-hood indirect calorimetry, body composition by bioimpedance analysis, body circumferences, fasting plasma glucose (FPG) and hemoglobin A(1c). Data were analyzed using stepwise multiple linear regression.

RESULTS

REE, corrected for weight, fat-free mass, age and gender, was significantly greater with FPG>10 mmol/l (P=0.017) and correlated with FPG (P=0.013) and hemoglobin A(1c) as percentage upper limit of normal (P=0.02). Weight was the main determinant of REE. Together with hip circumference and FPG, it explained 81% of the variation. FPG improved the predictability of the equation by >3%. With poor glycemic control, it can represent an increase in REE of up to 8%.

CONCLUSION

Our data indicate that in a population of obese subjects with type 2 diabetes mellitus, REE is better predicted when fasting plasma glucose is included as a variable.