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Articles by A. Vaag
Total Records ( 4 ) for A. Vaag
  A. C Alibegovic , L Hojbjerre , M. P Sonne , G van Hall , T. J Alsted , B Kiens , B Stallknecht , F Dela and A. Vaag
 

Individuals born with low birth weight (LBW) are at risk of developing type 2 diabetes mellitus (T2D), which may be precipitated by physical inactivity. Twenty-two LBW subjects and twenty-three controls were studied before and after bed rest by the hyperinsulinemic euglycemic clamp combined with indirect calorimetry and infusion of stable isotope tracers and preceded by an intravenous glucose tolerance test. LBW subjects had a similar body mass index but elevated abdominal obesity compared with controls. The basal rate of whole body lipolysis (WBL) was elevated in LBW subjects with and without correction for abdominal obesity before and after bed rest (all P = 0.01). Skeletal muscle hormone-sensitive lipase (HSL) protein expression and phosphorylation at Ser565 were similar in the two groups. Bed rest resulted in a decrease in WBL and an increased skeletal muscle HSL Ser565 phosphorylation indicating a decreased HSL activity in both groups. All subjects developed peripheral insulin resistance in response to bed rest (all P < 0.0001) with no differences between groups. LBW subjects developed hepatic insulin resistance in response to bed rest. In conclusion, increased WBL may contribute to the development of hepatic insulin resistance when exposed to bed rest in LBW subjects. Nine days of bed rest causes severe peripheral insulin resistance and reduced WBL and skeletal muscle HSL activity, as well as a compensatory increased insulin secretion, with no differences in LBW subjects and controls.

  A. C Alibegovic , M. P Sonne , L Hojbjerre , J Bork Jensen , S Jacobsen , E Nilsson , K Faerch , N Hiscock , B Mortensen , M Friedrichsen , B Stallknecht , F Dela and A. Vaag
 

Physical inactivity is a risk factor for insulin resistance. We examined the effect of 9 days of bed rest on basal and insulin-stimulated expression of genes potentially involved in insulin action by applying hypothesis-generating microarray in parallel with candidate gene real-time PCR approaches in 20 healthy young men. Furthermore, we investigated whether bed rest affected DNA methylation in the promoter region of the peroxisome proliferator-activated receptor- coactivator-1 (PPARGC1A) gene. Subjects were reexamined after 4 wk of retraining. We found that bed rest induced insulin resistance and altered the expression of more than 4,500 genes. These changes were only partly normalized after 4 wk of retraining. Pathway analyses revealed significant downregulation of 34 pathways, predominantly those of genes associated with mitochondrial function, including PPARGC1A. Despite induction of insulin resistance, bed rest resulted in a paradoxically increased response to acute insulin stimulation in the general expression of genes, particularly those involved in inflammation and endoplasmatic reticulum (ER) stress. Furthermore, bed rest changed gene expressions of several insulin resistance and diabetes candidate genes. We also observed a trend toward increased PPARGC1A DNA methylation after bed rest. We conclude that impaired expression of PPARGC1A and other genes involved in mitochondrial function as well as a paradoxically increased response to insulin of genes involved in inflammation and ER stress may contribute to the development of insulin resistance induced by bed rest. Lack of complete normalization of changes after 4 wk of retraining underscores the importance of maintaining a minimum of daily physical activity.

  P Poulsen , L. G Grunnet , K Pilgaard , H Storgaard , A Alibegovic , M. P Sonne , B Carstensen , H Beck Nielsen and A. Vaag
  OBJECTIVE

Genetic susceptibility, low birth weight (LBW), and aging are key etiological factors in the development of type 2 diabetes. LBW is common among twins. It is unknown whether twin status per se is associated with risk of type 2 diabetes, and valid concordance rates of type 2 diabetes in twins on a lifetime perspective are lacking.

RESEARCH DESIGN AND METHODS

A clinical study was done on a population-based cohort of same-sex elderly monozygotic (MZ) and dizygotic (DZ) twins (n = 297) and singleton control subjects (C) (n = 71) including measures of anthropometry and glucose tolerance. In addition, type 2 diabetes incidence cases in twins (n = 626) and singletons (n = 553) were identified through the National Diabetes Register.

RESULTS

Twins were more abdominally obese, insulin resistant, and glucose intolerant, as evidenced by a higher A1C (%) (means ± SD) (MZ: 6.0 ± 1.0, DZ: 5.8 ± 0.7, C: 5.6 ± 0.3, P = 0.004) and 120-min post–oral glucose tolerance test plasma glucose levels (in mmol/l) (MZ: 8.6 ± 4.6, DZ: 8.4 ± 3.9, C: 6.8 ± 2.4, P = 0.003) compared with singletons. Importantly, twins had a higher prevalence of type 2 diabetes (MZ: 17.5% [95% CI 14.4–20.6], DZ: 15.7% [13.1–18.3], C: 5.6% [3.0–8.2], P = 0.03) together with a 60% higher incidence rate of type 2 diabetes compared with singletons. Cumulative concordance rates of type 2 diabetes to the age of 84 years were similar among elderly MZ (0.76 [0.68–0.84]) and DZ (0.71 [0.63–0.78]) twins.

CONCLUSIONS

Twin status per se is associated with abdominal obesity, insulin resistance, and increased prevalence of type 2 diabetes in elderly twins. The data support a quantitatively significant impact of the fetal environment as opposed to genetics on risk of type 2 diabetes.

  K. Faerch , A. Vaag , D. R. Witte , T. Jorgensen , O. Pedersen and K. Borch-Johnsen
  Aims  Screening and prevention strategies for Type 2 diabetes require insight into the aetiological and potentially different risk factors leading to early impairments of fasting plasma glucose (FPG) and 2-h post-load plasma glucose (2hPG) levels. We studied whether risk factors predicting subtle elevations of FPG levels were different from those predicting elevations of 2hPG levels in men and women.

Methods  We used baseline and 5-year follow-up data from middle-aged men and women with normal glucose tolerance (NGT) at baseline in the Danish population-based Inter99 study (n = 3164). Anthropometric and non-anthropometric baseline predictors of the 5-year FPG and 2hPG levels were estimated in linear regression models stratified by gender.

Results  In men, but not in women, smoking and family history of diabetes predicted increased FPG levels, whereas high physical activity predicted a decline in 2hPG levels. Among the anthropometric variables, large waist circumference was the strongest predictor of increased FPG levels in men, whereas high body mass index (BMI) was the strongest predictor of increased FPG levels in women. In both men and women, BMI and waist circumference were equally strong in predicting 2hPG levels. Furthermore, short height predicted increased 2hPG levels in men, and short height and low hip circumference predicted increased 2hPG levels in women.

Conclusions  Risk factors that predict future FPG levels are different from those predicting future 2hPG levels. Furthermore, different risk factors predict glycaemic levels in men compared with women. These findings indicate that different aetiological pathways may lead to Type 2 diabetes in men and women.

 
 
 
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