Influence of Increasing BMI on Insulin Sensitivity and Secretion in Normotolerant Men and Women of a Wide Age Span

Abstract

The impact of sex and age on glucose metabolism in the development of overweight/obesity is a matter of debate. We hypothesized that insulin sensitivity (IS) and beta-cell function (BF) in a normal white population will differ between males and females and aimed to evaluate the possible effects of BMI and age on metabolic parameters of both sexes. This study is a cross-sectional analysis of the general community. IS was measured with quantitative insulin sensitivity check index (QUICKI) and oral glucose insulin sensitivity (OGIS) and BF with the insulinogenic index during 75-g 2-h oral glucose-tolerance tests (OGTTs). We studied 611 females and 361 males with normal glycemia according to both fasting and 2-h glucose (85 ± 0.3 mg/dl (means ± SE) in females and 89 ± 0.4 in males (P < 0.0001), and 93 ± 1 in females and 89 ± 1 in males (P = 0.005), respectively). Females were younger (37 ± 1 years) than males (40 ± 1, P < 0.0001), but no difference was found in mean BMI (BMI = 25.8 ± 0.2 kg/m2 in both). Student’s two-sample t-test was used for simple comparison between and within genders, multiple linear regressions to account for covariates. During the OGTT, females had lower glucose (area under the curve (AUC) 133 ± 1 mg/ml 2 h vs. 148 ± 2; P < 0.00001), while insulinemia was comparable (AUC 5.3 ± 0.1 mU/ml 2 h vs. 5.7 ± 0.2, P = 0.15). IS remained higher in females (473 ± 3 ml/min/m2 vs. 454 ± 3, P < 0.0001) also after having accounted for age and BMI (P = 0.015). No difference was observed in fasting insulin or BF. However, BF increased by 46% with BMI and when accounting for age and BMI, BF of females was significantly higher (P < 0.0001). Because IS and BF are higher in females than in males, sex should be considered in metabolic studies and overweight/obese populations

Quantification of excess risk for diabetes for those born in times of hunger, in an entire population of a nation, across a century

“…However, it was shown that in males, diabetes is diagnosed at a lower BMI than in females (26). Males are more insulin resistant and have more visceral and liver fat, which can contribute to their higher diabetes risk (27)(28)(29). These findings could partly explain the higher prevalence of diabetes seen in middle-aged and elderly men (30).…”

Gender‐based differences in glycaemic control and hypoglycaemia prevalence in patients with type 2 diabetes: results from patient‐level pooled data of six randomized controlled trials

“…When compared with men, women with normal glucose tolerance have been found to be more insulin-sensitive and have better -cell function; however, greater postmenopausal metabolic deterioration has been observed [1,2]. Gender-related differences have been measured using oral glucose tolerance testing, showing that in prediabetic states, women have higher rates of impaired glucose tolerance, whereas the rates of impaired fasting glucose are higher in men [3,4].…”

Insulin resistance and beta-cell dysfunction in people with prediabetes according to criteria based on glycemia and glycosylated hemoglobin

“…Use of participants' data for research purposes has been approved by the Hospital Management Committee. Part of the data were already included in previous studies [9,10].…”

“…From fasting samples, HbA1c was measured by the HA-8140 analyser (Menarini Diagnostics, Italy). Triglycerides, total cholesterol and low-and high-density lipoprotein cholesterol (LDL-C, HDL-C) were determined as previously described [9].…”