The association between tuberculosis and the development of insulin resistance in adults with pulmonary tuberculosis in the Western Sub-District of the Cape Metropole region

Philips, Lauren (2015-12)

Thesis (MNutr)--Stellenbosch University, 2015.

Thesis

ENGLISH SUMMARY : Introduction: The existence of a bi-directional relationship between tuberculosis (TB) and insulin resistance (IR)/diabetes has been alluded to in literature. Although diabetes has been linked to increased TB risk, the relationship between TB as a causative factor for IR remains unclear. The study aimed to determine if an association existed between TB and IR development in adults with newly diagnosed pulmonary tuberculosis (PTB) at baseline. It was additionally aimed to document changes in IR status during follow-up. Methods: This observational, cross-sectional study evaluated ambulatory participants at baseline for IR prevalence via anthropometrical and biochemical measures, together with diagnostic IR tests [homeostasis model assessment–IR (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI)]. In addition, a prospective cohort sub-section study was performed on approximately half of the baseline study population (n=29), who were followed-up at two and five months whilst on TB treatment. Summary statistics, correlation co-efficients and appropriate analysis of variance were used to describe and analyse data. Participants were excluded if they presented with other forms of TB, were HIV-positive, obese or had any pre-disposing IR conditions such as diabetes or metabolic syndrome. Results: A total of 59 participants were included from August 2013 until December 2014. The majority of participants were male (81.4%) and the mean age was 33.95 ±12.02 years. The prevalence of IR was 25.4% at baseline, determined by using a calculated HOMA-IR cut-off point of 2.477. Patients with IR were shown to be younger (p=0.04) and had a higher fasting insulin level (p<0.01). Although the difference between IR levels in participants between baseline and follow-up was not significant, a decrease was experienced over time. Most participants (61.0%) presented with a normal BMI at baseline and the majority of anthropometrical measurements showed a significant increase over the follow-up period, mainly in the first two months of treatment. The majority of participants (84.7%) had an increased mean CRP (60.18 ±50.92 mg/L) and decreased mean HDL-cholesterol level [69.5% (males: 0.94 ±0.88 mmol/L; females: 1.14 ±0.88 mmol/L)] at baseline. Mean baseline values of fasting glucose and albumin were within normal ranges (4.82 ±0.80 mmol/L and 39.32 ±4.35 g/L respectively). According to fasting glucose levels at baseline, 1.7% and 3.4% of participants presented with impaired fasting glucose and diabetes mellitus respectively. Several biochemical markers (CRP, albumin and white cell count) showed an improvement during the follow-up period. Conclusion: The study found an association between TB and IR development in newly diagnosed PTB patients. Many anthropometrical and biochemical measures showed improvements with time, especially during the intensive phase of treatment. Although not significant, IR levels decreased over time, which could be indicative of a clinical improvement. IR participants were shown to be younger and had a higher fasting insulin measurement. A high prevalence of IR among TB patients therefore highlights the need for early identification in order to facilitate a reversal of IR and prevent possible IR-related complications.

AFRIKAANSE OPSOMMING : Inleiding: Die tweerigtingverhouding tussen tuberkulose (TB) en insulienweerstandigheid (IW)/diabetes is al in literatuur beskryf. Diabetes hou wel verband met ’n verhoogde risiko vir TB, maar die rol van TB as oorsakende faktor vir IW bly onduidelik. Die doel van hierdie studie was om te bepaal of daar wel ’n verband bestaan tussen TB en die ontwikkeling van IW onder volwassenes met nuut gediagnoseerde pulmonale tuberkulose (PTB). ’n Addisionele doel was om enige veranderinge in die IW status, tydens opvolg ondersoeke, te dokumenteer. Metodes: Die waarneming, deursnee-studie het ambulante deelnemers tydens die basislyn periode geevalueer vir IW d.m.v antropometriese en biochemiese bepalings, asook diagnostiese IW toetse [“homeostasis model assessment–insulin resistance” (HOMA-IR) en die “quantitative insulin sensitivity check index” (QUICKI)]. ‘n Prospektiewe kohort sub-gedeelte studie is ook uitgevoer op ongeveer die helfte van die basislyn studiepopulasie (n=29), wat op twee en vyf maande opgevolg was tydens TB behandeling. Beskrywende statistiek, korrelasie koeffisiente en toepaslike analises van variansie is gebruik om data te beskryf en analiseer.Deelnemers is uitgesluit indien hulle met enige ander vorm van TB gediagnoseer is, MIV-positief of vetsugtig was of presenteer het met enige predisponerende IW toestande, soos diabetes of metaboliese sindroom. Resultate: Nege en vyftig deelnemers is ingesluit tussen Augustus 2013 en Desember 2014. Die meerderheid was manlik (81.4%) met ’n gemiddelde ouderdom van 33.95 ±12.02 jaar. Die basislyn prevalense van IW was 25.4%, bepaal deur ’n berekende HOMA-IR afsnypunt van 2.477. IW pasiente was jonger (p=0.04) en besit ’n hoer vastende insulienvlak (p<0.01). Alhoewel daar geen beduidende verskil in die IW vlakke tussen basislyn en opvolg periodes was nie, was daar wel ’n afname waargeneem oor tyd. Die meeste deelnemers (61.0%) het ’n normale LMI by basislyn gehad. Die meerderheid antropometriese metings het ‘n beduidende toename getoon tydens die opvolg periode, hoofsaaklik in die eerste twee maande van behandeling. Die meerderheid deelnemers (84.7%) het ‘n verhoogde gemiddelde CRP (60.18 ±50.92 mg/L) en ‘n verlaagde gemiddelde HDL-cholesterolvlak [69.5% (mans: 0.94 ±0.88 mmol/L; vrouens: 1.14 ±0.88 mmol/L)] by basislyn getoon. Die gemiddelde basislyn waardes van vastende glukose en albumien was binne normale perke (4.82 ±0.80 mmol/L en 39.32 ±4.35 g/L onderskeidelik). Volgens die basislyn vastende glukosevlakke, is 1.7% met ingekorte vastende glukose en 3.4% met diabetes mellitus geklassifiseer. Verskeie biochemiese aanduiders (CRP, albumien en witsel-telling) het ‘n verbetering tydens die opvolg periode getoon. Gevolgtrekking: Hierdie studie het ‘n assosiasie tussen TB en IW-ontwikkeling, in nuut gediagnosserde PTB pasiente, getoon. Verskeie antropometriese en biochemiese metings het verbeter met tyd, veral tydens die intensiewe fase van behandeling. Alhoewel nie beduidend, het IW vlakke met tyd afgeneem, wat moontlik ‘n kliniese verbetering aandui. Deelnemers met IW was jonger en het hoer vastende insulien vlakke getoon. Hoe voorkoms van IW onder TB pasiente beklemton die behoefte vir vroee identifisering, om sodoende, ‘n omkering in IW te fasiliteer en IW-verwante komplikasies, waar moontlik, te voorkom.

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