Gender modulates the relationship between body weight and plasma glucose in overweight or obese subjects.

Obesity and weight increase during adult life are strong predictors of type 2 diabetes. Whether fasting plasma glucose (FPG) is likewise related to body weight as well as with its increase during the adult life in obese-overweight people and whether this relationship is different between the genders is the question asked by the present study. We measured FPG in 1063 overweight-obese subjects (395M/668F) with BMI > or =25 kgm(-2) and classified with no history of diabetes and with a FPG< 7 mmol/l, who consequently came to the Outpatient Clinic of our Diabetes Unit to obtain dietetic advice. Weight increase was determined as the difference between actual weight and weight at 18 years (weight-diff), including only patients with weight-diff> 0. By univariate analysis age, BMI, waist circumference and weight change were loosely related to FPG in both sexes, even if the relation between plasma glucose and anthropometric variables was more consistent in females. By multivariate regression analysis, after adjusting for age, waist circumference, menopausal status and smoking habit, FPG was significantly related to both waist circumference and weight-diff only in women. Odds Ratio for fasting hyperglycaemia (FPG> 6.11 mmol/l), for each S.D. unit increase in weight-diff, after adjusting for age, waist circumference, smoking habit and menopausal status was 1.272; 95% CI: 0.863-1.901 (p=ns) for males and 1.800; 95% CI: 1.239-2.652 (p=0.002) for women. In conclusion our findings suggest that in non-diabetic overweight-obese people, after controlling for main cofounders, anthropometric variables and in particular waist circumference and weight change after 18 years are linearly related to FPG in women, independently predicting the risk of fasting hyperglycaemia only in these latter.

Normal glucose tolerance and gestational diabetes mellitus: what is in between?

OBJECTIVE: The aim of this article was to define the metabolic phenotype of pregnant women with one abnormal value (OAV) during an oral glucose tolerance test (OGTT) and to test whether OAV could be considered metabolically comparable to gestational diabetes mellitus (GDM) or a specific entity between GDM and normal pregnancy. RESEARCH DESIGN AND METHODS: After 100-g 3-h OGTTs, 4,053 pregnant women were classified as having GDM, OAV, or normal glucose tolerance (NGT). Those with OAV were subdivided into three subgroups: fasting hyperglycemia (one abnormal value at fasting during an OGTT), 1-h hyperglycemia (one abnormal value at 1 h during an OGTT [1h-OAV]), or 2- or 3-h hyperglycemia (one abnormal value at 2 or 3 h during an OGTT). As derived from the OGTT, we measured insulin sensitivity (insulin sensitivity index [ISI] Matsuda) and insulin secretion (homeostasis model assessment for the estimation of beta-cell secretion [HOMA-B], first- and second-phase insulin secretion). The product of the first-phase index and the ISI was calculated to obtain the insulin secretion-sensitivity index (ISSI). RESULTS: GDM was diagnosed in 17.9% and OAV in 18.7% of pregnant women; women with GDM and OAV were older and had higher BMI and serum triglyceride levels than those with NGT (all P < 0.05). Women with NGT had the highest ISI followed by those with OAV (-21.7%) and GDM (-32.1%). HOMA-B results were comparable with those for OAV and GDM but significantly (P < 0.01) lower than those for NGT; first- and second-phase insulin secretion appeared progressively reduced from that in women with NGT to that in women with OAV and GDM (P < 0.01). ISSI was higher in women with NGT than in women with either OAV (-34%) or GDM (-51.7%) (P < 0.001). Among OAV subgroups, the 1h-OAV subgroup showed the lowest ISSI (P < 0.05). CONCLUSIONS: OAV and GDM are clinically indistinguishable, and both groups are different from women with NGT. Women with GDM and OAV showed impaired insulin secretion and insulin sensitivity, although these defects are more pronounced in women with GDM. Compared with other OAV subgroups, 1h-OAV could be considered a more severe condition.

Taurine in women with a history of gestational diabetes.

Taurine is the most abundant amino acid in the human body and seems to play an important role in increasing glucose-mediated insulin secretion, as well as in programming beta-cell maturation during the prenatal life in utero. To test the hypothesis that plasma taurine is related to glucose tolerance, insulin sensitivity and insulin secretion in subjects with history of beta-cell dysfunction such as women with history of gestational diabetes (GDM), we studied 72 non-diabetic women with history of GDM (n=43), impaired glucose tolerance (IGT; n=7), and normal glucose tolerance (NGT; n=22) as previously classified by a 100g-3h-OGTT performed between the 24th and the 28th gestational week. Insulin sensitivity (ISIogtt, calculated through Matsuda-DeFronzo index) and a proxy for insulin secretion (basal plasma C-peptide/fasting plasma glucose; CP/glucose) were measured during and after pregnancy. Plasma taurine was measured after a median period of 6 years (2-11 years) from index pregnancy, when glucose tolerance was retested by a 75 g-2h-OGTT. Plasma taurine was significantly lower in women who had experienced GDM and was unrelated to ISIogtt. Moreover, plasma taurine was inversely related to previous gestational area-under-curve of glucose and directly related to post-gestational CP/glucose, as well to CP/glucose measured during pregnancy (p<0.05 for both). The relative risk of altered glucose metabolism during previous pregnancies (IGT+GDM) was higher as plasma taurine decreased, even after adjusting for age, time-lag from pregnancy, body mass index and family history of diabetes (OR: 0.980; CI 95%: 0.963-0.999, p=0.003). In conclusion plasma taurine seems to be a fair marker of altered glucose metabolism during past pregnancies in women with antecedent GDM and appears to be inversely related to the previous as well as to the actual insulin secretion in these subjects.

Respiratory muscles and dyspnea in obese nonsmoking subjects.

To our knowledge no data have been reported on the contribution to acute increase in dyspnea by the respiratory muscles in obese nonsmoking subjects. To better focus on this topic, we studied seven obese subjects and an age-matched normal control group, assessing baseline pulmonary function, breathing pattern, esophageal pressure (Pes), and gastric (Pga) and transdiaphragmatic (Pdi) pressures. Pes was also recorded during a sniff maneuver (Pessn). During a hypercapnic rebreathing test we recorded inspiratory swing in Pes (Pessw), expiratory changes in Pga, and inspiratory swings in Pdi (Pdisw). Change in inspiratory capacity was considered the mirror image of end-expiratory lung volume (EELV). Dyspnea was assessed by a modified Borg scale. Under control conditions, patients exhibited a reduced expiratory reserve volume and intrinsic positive end-expiratory pressure (PEEPi). At the end of hypercapnic stimulation, compared with controls our obese subjects exhibited greater respiratory frequency (Rf), shorter expiratory time, greater Pessw, and lower Pdisw. Increases in EELV and PEEPi were found in the obese subjects but not in controls. Changes in Borg correlated with changes in PETCO2, VE, Pessw (%Pessn), and Pdisw to a greater extent in patients than in controls. Stepwise regression analysis indicated the amount of variability in Borg that was predicted by both Pdisw (r2 = 0.31, p < 0.0004), and Pessw (%Pessn) (r2 = 0.09, p < 0.005) in controls, and by Pessw (%Pessn) (r2 = 0.40, p < 0.00001) in obese subjects. We conclude that the rib cage muscles contributed to dyspnea to a greater extent in this subset of obese subjects.