Insulin sensitivity and secretion in normal children related to size at birth, postnatal growth, and plasma insulin-like growth factor-I levels

Evaluation of Metabolic Control in Women with Gestational Diabetes Mellitus by the Continuous Glucose Monitoring System: A Pilot Study

OBJECTIVE

To evaluate the blood glucose concentrations in a group of women with gestational diabetes mellitus (GDM), by the use of a continuous glucose monitoring system (CGMS).

METHODS

Seven women with diet-controlled GDM (group G1), 5 with diet- and insulin-controlled GDM (group G2), and 7 healthy, pregnant women (group N) were included in the study. The treatment was adjusted on the basis of self-monitoring of blood glucose (SMBG). The self-monitoring was performed 4 times a day, with the goals of fasting blood glucose values of <90 mg/dL and postprandial (2 hours after each meal) values of <120 mg/dL. Then patients were submitted to a 72-hour period of use of the CGMS.

RESULTS

In the 3 study groups--N, G1, and G2, respectively--no significant differences were noted in individual study parameters, measured with the CGMS in regard to the following: mean 24-hour glycemia (85, 87, and 91 mg/dL), fasting blood glucose (79, 88, and 82 mg/dL), postprandial glucose (96, 97, and 105 mg/dL), mean glucose level during the night (77, 71, and 75 mg/dL), and area under the glycemia curve (281, 315, and 310). Moreover, no significant difference was found in the total duration of glycemia below 60 mg/dL (317, 300, and 370 minutes) or the duration of glycemia of more than 120 mg/dL (259, 225, and 394 minutes) in group N, G1, and G2, respectively. With use of the CGMS, however, in comparison with SMBG, a wider range of glycemic levels was observed in all 3 study groups: for the healthy, pregnant women, 41 to 194 mg/dL versus 61 to 151 mg/dL; for G1, 40 to 244 mg/dL versus 40 to 180 mg/dL; and for G2, 40 to 173 mg/dL versus 50 to 157 mg/dL.

CONCLUSION

The therapy, based on SMBG levels, when applied to the group of women with GDM, brought the glucose levels under effective control, with mean outcome values similar to those observed in the group of normal pregnant women. Nevertheless, using the CGMS, we detected long, asymptomatic periods of high and low blood glucose levels, both in the patients with GDM and in the unaffected pregnant women. The use of the CGMS for monitoring blood glucose profiles might be beneficial in this group of pregnant women.

Insulin resistance in pre-school very-low-birth weight pre-term children

AIMS

To evaluate the metabolic pattern of a group of pre-school small- (SGA) and appropriate-for-gestational age (AGA) pre-term very-low-birthweight (VLBW) (<1500 gr) Italian children and retrospectively verify if the growth rate in the first years of life is associated to the laboratory and anthropometric characteristics of these children.

METHODS

58 (16 SGA, 42 AGA) VLBW children, without major congenital malformations/conditions were enrolled; their anthropometric, clinical and (in 34 of them) laboratory characteristics were evaluated at pre-school age (> 2<6 years of corrected age).

RESULTS

Clinical, anthropometric and laboratory characteristics at pre-school age were similar in SGA and AGA. Sixty-nine percent of SGA and 51% of AGA children showed a significant weight centile crossing (CC) at 24 months. Fasting serum glucose, insulin and insulin resistance (evaluated by the Homeostasis Model Assessment -HOMA-IR-) were higher in AGA and SGA with CC. The increment in weight standard deviation scores from birth-to-24 months was significantly associated with pre-school BMI SDS, waist, fasting insulin, and HOMA-IR values, both in unadjusted and adjusted models. In a multiple regression model, after multiple adjustments, this increment is the only significant predictor of pre-school insulin (B = 0.19; 95%CI 0.07-0.31; P = 0.006) and HOMA-IR levels (B = 0.20; 95%CI 0.08-0.32; P = 0.004) both in SGA and AGA children.

CONCLUSIONS

The adverse metabolic pattern of pre-school VLBW children seems related to post-natal events (rapid weight growth) independently by their being small- or appropriate-for gestational age.

Type 2 diabetes mellitus in youth: the complete picture to date

Type 2 diabetes mellitus is a heterogeneous condition in which the clinical manifestation of hyperglycemia is a reflection of the impaired balance between insulin sensitivity and insulin secretion. Clinical experience and research in youth type 2 diabetes mellitus are in an early stage because of the relative novelty of the condition in pediatrics. This article discusses the amassed information in type 2 diabetes mellitus of youth to date with respect to the epidemiology, pathophysiology, risk factors, clinical presentation, screening, and management strategies.

Longitudinal changes in insulin sensitivity and secretion from birth to age three years in small- and appropriate-for-gestational-age children

AIMS/HYPOTHESIS

Insulin resistance and type 2 diabetes risk in human subjects who were small-for-gestational-age (SGA) at birth may be a consequence of rapid early postnatal weight gain.

MATERIALS AND METHODS

We prospectively studied early changes in fasting insulin sensitivity and insulin secretion, assessed by a short intravenous glucose tolerance test that was conducted several times from birth to 3 years of age in 55 SGA (birthweight below fifth percentile) newborns and in 13 newborns with a birthweight appropriate for gestational age (AGA).

RESULTS

Most SGA infants showed postnatal upward weight centile crossing and by 3 years were similar in size to AGA infants. SGA infants had lower pre-feed insulin levels at postnatal age 48 h than AGA infants (median 34.4 vs 59.7 pmol/l, p<0.05), but by the age of 3 years they had higher fasting insulin levels (median 38.9 vs 23.8 pmol/l, p<0.005), which were related to rate of weight gain between 0 and 3 years (r=0.47, p=0.0003). First-phase insulin secretion did not differ between SGA and AGA infants, but SGA infants had a lower glucose disposition index (beta cell compensation) (median 235 vs 501 min mmol(-1) l(-1), p=0.02), which persisted after allowing for postnatal weight gain (p=0.009).

CONCLUSIONS/INTERPRETATION

SGA infants showed a marked transition from lower pre-feed insulin and increased insulin sensitivity at birth to insulin resistance over the first 3 years of life. This transition was related to rapid postnatal weight gain, which could indicate a propensity to central fat deposition. The additional observation of reduced compensatory beta cell secretion underlines the need for long-term surveillance of glucose homeostasis in all SGA subjects, whether or not they show postnatal catch-up growth.

Growth hormone therapy in short children born small for gestational age

Being born small for gestational age (SGA) is one of the most common causes of childhood short stature, and recombinant GH therapy has been recently licensed to promote growth in short SGA children from the age of 4 years old. Studies are now reporting very encouraging effects on adult height gains, especially in those children who started GH therapy early, at least 2 years prior to the onset of puberty. Compared to the age at starting treatment, the GH dose has a less significant impact on final height, and more attention needs to be paid now to identify earlier those SGA children who fail to catch-up spontaneously. The benefits are not just in terms of height, but also in body composition and possibly blood pressure and lipid levels. However the risk of side effects and long-term complications, particularly related to the expected metabolic effects of GH in inducing insulin resistance and hyperinsulinaemia, need to be carefully monitored especially in SGA children with a family history of type 2 diabetes. Recently, GH therapy was found to amplify the adrenarche of short SGA children and to induce a pro-inflammatory shift, as judged by a rise of neutrophil count and circulating interleukin-6 (IL-6), and a fall in adiponectin levels. Further progress is anticipated to assess the addition of insulin-sensitizing therapy to attenuate the GH-induced hyperinsulinemia, in order to alter the pro-inflammatory course, to avoid excessive release of adrenal androgens, and to slow down the potential rapid tempo of pubertal progression in SGA children. In the meantime, post-SGA short stature is rapidly becoming one of the prime indications for GH therapy in childhood.

Endocrine and metabolic consequences of intrauterine growth retardation

Size at birth and early infancy growth rates have been linked to long-term risks for diseases, such as type 2 diabetes and cardiovascular disease. These associations could be explained by permanent programming of metabolic responses and selective survival of those genetically predisposed to such adaptations. These epidemiologic associations may also affect long-term disease risk in short small-for-gestational age children, who are often treated with growth hormone. Study of the mechanisms and genetic factors involved in the association between small size at birth, rapid postnatal weight gain, and adult disease may promote the early identification of subjects with the highest disease risk and new opportunities to develop targeted early interventions.

Effects of obesity on growth and puberty

Nutrition is an important regulator of the tempo of human growth. Infancy may represent a critical "window" where variations in nutrition have longer-term consequences for growth and development. Rapid weight gain during infancy is associated with accelerated growth and early pubertal development. Rapid weight gain in infancy is also associated with the development of insulin resistance and an exaggerated adrenarche. Such circulating hormonal changes, together with elevated leptin levels and integral effects of fat cells on hormone action through local 11beta-steroid dehydrogenase and aromatase activity could effect rate of progression of pubertal development in obese subjects. The secular trends in growth and maturation are partly attributed to changing nutrition. Recent data suggest that age at menarche may be static, but there is a debate as to whether the first signs of puberty are being seen much earlier in obese girls. Rapid early weight gain, obesity and early development may have implications for later health through the development of PCOS and overall association with cancer risk.

The developmental origins of adult disease

Epidemiological and clinical observations have led to the hypothesis that the risk of developing some chronic diseases in adulthood is influenced not only by genetic and adult lifestyle factors, but also by environmental factors acting in early life. These factors act through the processes of developmental plasticity and possibly epigenetic modification, and can be distinguished from developmental disruption. The concept of predictive adaptation has been developed to explain the relationship between early life events and the risk of later disease. At its base, the model suggests that a mismatch between fetal expectation of its postnatal environment and actual postnatal environment contribute to later adult disease risk. This mismatch is exacerbated, in part, by the phenomenon of "maternal constraint" on fetal growth, which implicitly provides an upper limit of postnatal nutritional environment that humans have adapted for and is now frequently exceeded. These experimental, clinical and conceptual considerations have important implications for prevention and intervention in the current epidemic of childhood obesity and adult metabolic and cardiovascular disorders.

Lower Birth Weight and Visceral Fat Accumulation Are Related to Hyperinsulinemia and Insulin Resistance in Obese Japanese Children

This study aimed to reveal the relation of birth weight (or the birth weight standard deviation score [BWSDS]) and visceral fat accumulation to hyperinsulinemia and insulin resistance. We examined obese Japanese children (650 boys and 317 girls) with a mean age of 10.3 years (range, 6-15 years). The mean percentage of overweight to the standard body weight of Japanese children was 52.1% in boys and 51.4% in girls. Abdominal fat thickness (maximum preperitoneal fat thickness; Pmax) was measured using ultrasonography. The fasting serum insulin and plasma glucose levels were measured, and the homeostasis model assessment-insulin resistance (HOMA-R) and quantitative insulin sensitivity check index (QUICKI) were calculated. We divided the subjects into four groups according to their birth weight or BWSDS, and compared anthropometric measurements, Pmax, blood pressure, serum insulin levels, HOMA-R and QUICKI among the quartiles. The relationships of both birth weight (or BWSDS) and Pmax to serum insulin levels (or HOMA-R, QUICKI) were examined with multiple regression analyses. The fasting serum insulin level and HOMA-R were highest in the quartile with the lowest birth weight or BWSDS. The birth weight and BWSDS were inversely related to the serum insulin levels and HOMA-R, positively related to QUICKI, and independent of Pmax. Our findings suggest that both lower birth weight and visceral fat accumulation may be independently related to hyperinsulinemia and insulin resistance in obese Japanese children.