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Seasonal variations of insulin sensitivity from a euglycemic insulin clamp in elderly men
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Uppsala kliniska forskningscentrum (UCR). Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Geriatrik.
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinska vetenskaper. (Endokrin diabetes och metabolism)
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Allmänmedicin och klinisk epidemiologi.
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Uppsala kliniska forskningscentrum (UCR).
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2012 (Engelska)Ingår i: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 117, nr 1, s. 35-40Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Introduction

Seasonal variations in hemoglobin-A1c have been reported in diabetic patients, but the underlying mechanisms have not been elucidated.

Aims

To study if insulin sensitivity, insulin secretion, and fasting plasma glucose showed seasonal variations in a Swedish population-based cohort of elderly men.

Methods

Altogether 1117 men were investigated with a euglycemic insulin clamp and measurements of fasting plasma glucose and insulin secretion after an oral glucose tolerance test. Values were analyzed in linear regression models with an indicator variable for winter/summer season and outdoor temperature as predictors.

Results

 During winter, insulin sensitivity (M/I, unit = 100 × mg × min-1 × kg-1/(mU × L-1)) was 11.0% lower (4.84 versus 5.44, P = 0.0003), incremental area under the insulin curve was 16.4% higher (1167 versus 1003 mU/L, P = 0.007). Fasting plasma glucose was, however, not statistically significantly different (5.80 versus 5.71 mmol/L, P = 0.28) compared to the summer season. There was an association between outdoor temperature and M/I (0.57 units increase (95% CI 0.29–0.82, P < 0.0001) per 10°C increase of outdoor temperature) independent of winter/summer season. Adjustment for life-style factors, type 2 diabetes, and medication did not alter these results.Read More:http://informahealthcare.com/doi/abs/10.3109/03009734.2011.628422

Conclusions

Insulin sensitivity showed seasonal variations with lower values during the winter and higher during the summer season. Inverse compensatory variations of insulin secretion resulted in only minor variations of fasting plasma glucose. Insulin sensitivity was associated with outdoor temperature. These phenomena should be further investigated in diabetic patients.

Ort, förlag, år, upplaga, sidor
2012. Vol. 117, nr 1, s. 35-40
Nyckelord [en]
Seasonal variations, insulin sensitivity, clamp, insulin secretion, temperature
Nationell ämneskategori
Endokrinologi och diabetes Geriatrik
Identifikatorer
URN: urn:nbn:se:uu:diva-165044DOI: 10.3109/03009734.2011.628422ISI: 000300304000006PubMedID: 22066936OAI: oai:DiVA.org:uu-165044DiVA, id: diva2:471452
Tillgänglig från: 2012-01-02 Skapad: 2012-01-02 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
Ingår i avhandling
1. Measurement Variability Related to Insulin Secretion and Sensitivity: Assessment and Implications in Epidemiological Studies
Öppna denna publikation i ny flik eller fönster >>Measurement Variability Related to Insulin Secretion and Sensitivity: Assessment and Implications in Epidemiological Studies
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

There is a growing interest in random measurement variability of biological variables. In regression models, such variability of the predictors yields biased estimators of coefficients (regression dilution bias). The objectives of this thesis were to develop an efficient method to correct for such bias, to reveal the relative importance of insulin sensitivity and insulin secretion, corrected for regression dilution bias, on glucose tolerance, and to explore the seasonal nature of the variability of insulin sensitivity.

A reliability study is often designed to randomly select subjects from the main study. Our idea was to collect replicates for subjects with extreme values on their first measurement. The extreme selection design, in combination with maximum likelihood estimation, resulted in an efficient estimator of a corrected regression coefficient in a simple linear regression model. Results were presented theoretically and with an application: The relation between insulin sensitivity and fasting insulin in Uppsala Longitudinal Study of Adult Men (ULSAM) where the extreme selection design decreased the standard error of the estimated regression coefficient with 28 per cent compared with the random sampling design.

We estimated the partial longitudinal effects of the predictors insulin sensitivity and insulin secretion, corrected for regression dilution bias, on glucose tolerance in ULSAM. The effects of the predictors, when corrected, were similar.

Insulin sensitivity in ULSAM increased during summer and decreased during winter and insulin secretion exposed opposite variation keeping glucose homeostasis nearly constant. Insulin sensitivity was related to outdoor temperature.

In summary, we developed a cost-efficient reliability design for correction for regression dilution bias. Insulin sensitivity and insulin secretion had similar longitudinal effects on glucose tolerance, which implies that interventions aimed at these targets are equally important. Further, we revealed the seasonal nature of variations of insulin sensitivity and insulin secretion. This result has implications on glycaemic control in diabetic patients.

Ort, förlag, år, upplaga, sidor
Uppsala: Acta Universitatis Upsaliensis, 2009. s. 67
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 440
Nationell ämneskategori
Geriatrik
Forskningsämne
Geriatrik
Identifikatorer
urn:nbn:se:uu:diva-99636 (URN)978-91-554-7469-0 (ISBN)
Disputation
2009-04-29, Enghoffsalen, Akademiska sjukhuset, Uppsala, 13:15 (Svenska)
Opponent
Handledare
Tillgänglig från: 2009-04-07 Skapad: 2009-03-18 Senast uppdaterad: 2012-07-26Bibliografiskt granskad

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Berglund, LarsBerne, ChristianSvärdsudd, KurtGarmo, HansMelhus, HåkanZethelius, Björn

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Berglund, LarsBerne, ChristianSvärdsudd, KurtGarmo, HansMelhus, HåkanZethelius, Björn
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Uppsala kliniska forskningscentrum (UCR)GeriatrikInstitutionen för medicinska vetenskaperAllmänmedicin och klinisk epidemiologi
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Upsala Journal of Medical Sciences
Endokrinologi och diabetesGeriatrik

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