Insulin-like growth factor I, binding proteins -1 and -3, risk of type 2 diabetes and macronutrient intakes in men.

The insulin-like growth factor (IGF) axis may be involved in the development of type 2 diabetes. We examined the associations of IGF-I and IGF binding proteins (IGFBP)-1 and -3 with diabetes risk and evaluated macronutrient intakes related to the observed associations. In a nested case-control study of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish male smokers aged 50-69 years, the IGF variables were measured from baseline serum samples for a random sample of 310 men with diabetes diagnosed during a 12-year follow-up and for 310 controls matched by age, recruitment day and intervention group. Diet at baseline was assessed using a validated FFQ. The associations of IGF proteins with diabetes risk were estimated using conditional logistic regression and the associations with macronutrient intakes using linear regression. IGF-I and IGFBP-3 were not associated with the incidence of diabetes. Higher IGFBP-1 was associated with lower diabetes risk in an unadjusted crude model (OR 0·25; 95 % CI 0·15, 0·42 in the highest quartile compared with the lowest), but not after adjustment for BMI (corresponding OR 0·76; 95 % CI 0·41, 1·40). Intakes of carbohydrates, plant protein and milk protein associated positively and intake of meat protein and fat negatively with IGFBP-1 (P<0·005). IGFBP-1 was inversely associated with diabetes risk, but the association was substantially dependent on BMI. The associations between macronutrient intakes and IGFBP-1 may reflect influences of nutrients or foods on insulin concentrations.

Glycaemic index, carbohydrate substitution for fat and risk of CHD in men.

We have examined the associations between dietary glycaemic index (GI), substitutions of total, low-, medium- and high-GI carbohydrates for fat and the risk of CHD. The study consisted of 21 955 male smokers, aged 50-69 years, within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The diet was assessed at baseline using a validated FFQ. During a 19-year follow-up, 4379 CHD cases (2377 non-fatal myocardial infarctions and 2002 CHD deaths) were identified from national registers. Relative risks (RR) and CI for CHD were analysed using Cox proportional hazards modelling, and multivariate nutrient density models were applied to examine the associations between the substitutions of macronutrients and the risk of CHD. Dietary GI was inversely associated with CHD risk: multivariate RR in the highest v. lowest quintile was 0·89 (95 % CI 0·81, 0·99). Replacement of higher-GI carbohydrates with lower-GI carbohydrates did not associate with the risk. Replacing saturated and trans-fatty acids with carbohydrates was associated with decreased CHD risk: RR for substitution of 2 % of energy intake was 0·97 (95 % CI 0·94, 0·99). On the contrary, replacing MUFA with carbohydrates was associated with an increased risk: RR for substitution of 2 % of energy intake was 1·08 (95 % CI 1·01, 1·16). We conclude that in the present study population, contrary to the hypothesis, a lower GI does not associate with a decreased risk of CHD. The associations of carbohydrates with CHD risk depend on the fatty acid composition of the diet.

Low-, medium- and high-glycaemic index carbohydrates and risk of type 2 diabetes in men.

Findings on dietary glycaemic index (GI) and glycaemic load (GL) as risk factors for type 2 diabetes have been controversial. We examined the associations of dietary GI and GL and the associations of substitution of lower-GI carbohydrates for higher-GI carbohydrates with diabetes risk in a cohort of Finnish men. The cohort consisted of 25 943 male smokers aged 50-69 years. Diet was assessed, at baseline, using a validated diet history questionnaire. During a 12-year follow-up, 1098 incident diabetes cases were identified from a national register. Cox proportional hazard modelling was used to estimate the risk of diabetes, and multivariate nutrient density models were used to examine the effects of substitution of different carbohydrates. Dietary GI and GL were not associated with diabetes risk; multivariate relative risk (RR) for highest v. lowest quintile for GI was 0·87 (95 % CI 0·71, 1·07) and for GL 0·88 (95 % CI 0·65, 1·17). Substitution of medium-GI carbohydrates for high-GI carbohydrates was inversely associated with diabetes risk (multivariate RR for highest v. lowest quintile 0·75, 95 % CI 0·59, 0·96), but substitution of low-GI carbohydrates for medium- or high-GI carbohydrates was not associated with the risk. In conclusion, dietary GI and GL were not associated with diabetes risk, and substitutions of lower-GI carbohydrates for higher-GI carbohydrates were not consistently associated with a lower diabetes risk. The associations of dietary GI and GL with diabetes risk should be interpreted by considering nutritional correlates, as foods may have different properties that affect risk.

Effect of alpha-tocopherol and beta-carotene supplementation on macrovascular complications and total mortality from diabetes: results of the ATBC Study.

AIM: To determine whether alpha-tocopherol or beta-carotene supplementation affects diabetic macrovascular complications and total mortality. METHODS: This study was carried out as part of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a double-blind, randomized trial with a 2x2 factorial design. A total of 29,133 middle-aged male smokers received either vitamin E 50 mg/day or beta-carotene 20 mg/day, or both, or placebo for a median of 6.1 years. At base-line, 1700 men had type 2 diabetes. Of these men, 662 were diagnosed with first-ever macrovascular complication, and 1142 died during the 19-year follow-up. RESULTS: Neither supplementation affected the risk of macrovascular complication or total mortality during the intervention period. For the alpha-tocopherol-supplemented versus no alpha-tocopherol-supplemented, and beta-carotene-supplemented versus no beta-carotene-supplemented we found relative risk (RR) 0.84 (95% confidence interval (CI) 0.65-1.10) and RR 1.15 (95% CI 0.89-1.50) for macrovascular complication, respectively, and RR 1.00 (95% CI 0.80-1.25) and RR 1.06 (95% CI 0.85-1.33) for total mortality, respectively. No essential changes were found in these effects when the follow-up was extended up to 19 years. CONCLUSION: Alpha-tocopherol or beta-carotene supplementation has no protective effect on macrovascular outcomes or total mortality of diabetic male smokers.