Participants
This cross-sectional study was a part of a larger study concerning inflammation, endothelial function and microbiota in PLWH with DM2 [16, 17]. Participants were included between August 2012 and August 2013. In total 100 participants were included in the primary study. When included all participants were invited to a Dual-energy X-ray absorptiometry scan (DXA-scan) which were optional. In total 80 participants agreed to this (18 with HIV+DM2+, 18 with HIV+DM2-, 19 controls with DM2 and 25 healthy controls). All 80 participants with a DXA-scan were included in the present study. This was a part of a larger study and the present study was designed as an exploratory study. Thus, a power calculation was not done for outcomes presented in this study.
Inclusion criteria for PLWH were treatment with cART and undetectable viral replication (defined as HIV RNA < 200 copies/mL). Inclusion criteria for persons with DM2 were confirmed DM2 by a trained clinician and one or more of the following: HbA1c≥ 48mmol/mol, fasting venous plasma glucose >7 mmol/l, or 2-hour venous plasma glucose concentration on ≥ 11.1 mmol/L after a glucose tolerance test prior to this study [18]. All persons with DM2 were treated with diet and/or oral anti-diabetics and/or insulin. All persons without DM2 were required to have both normal fasting venous plasma glucose (<6.1 mmol/L) and HbA1c < 48 mmol/mol. We did not have to exclude any participants without DM2 included in the study due to elevated plasma glucose level or HbA1c
Exclusion criteria were immunosuppressive treatment, acute infections, malignancy, and pregnancy. However, no females in the reproductive age group were included in the study. Both written and oral information was given to the study participants prior to inclusion in the study. This included instructions about at least 10-hours fasting before time of blood sampling.
All PLWH with DM2 attending routine control for HIV infection at the Department of Infectious Diseases at University Hospital of Copenhagen, Rigshospitalet or Hvidovre Hospital, and who fulfilled inclusion and exclusion criteria, were invited to participate in the study until n=25 were recruited in this group. Inclusion of patients and controls in the other groups was done to achieve best possible match on age and sex. Persons with DM2 were included from the Department of Endocrinology and Centre of Inflammation and Metabolism, University Hospital of Copenhagen, Rigshospitalet. Healthy controls were recruited among hospital staff. All PLWH included in the study had a confirmatory positive HIV test. A negative HIV test was not required for participants in the uninfected control groups, since the prevalence of HIV in Denmark is 0.1%, and it seems reasonable to assume that clinically healthy persons are HIV-negative. Six controls with DM2 also participated in a study concerning the effect of short duration, high-intensity interval training on endothelial function and metabolism[19]. These participants were included before training.
The study was performed in accordance with the Declaration of Helsinki and approved by the local ethical committee on health research ethics (H-4-2012-076 CIM VEK) and the Danish Data Protection Agency.
Dual-energy X-ray absorptiometry scan
A DXA–scan was used to measure total fat mass, limb fat mass, and trunk fat mass in all participants (Lunar Prodigy Advance; GE Medical Systems Lunar, Milwaukee, WI, USA). Prodigy Software (enCORE 2004, version 8.8, GE Lunar Corp., Madison, WI, USA).
Laboratory analyses
Fasting venous blood samples were collected from all participants. HIV RNA was measured in PLWH, and glucose, HbA1c, triglyceride, cholesterol, HDL, LDL, c-peptide, CD4+, and CD8+ counts were measured in all participants as routine analyses at the time of inclusion at the Department of Clinical Biochemistry at Rigshospitalet, Denmark. Tubes with sodium fluoride and potassium oxalate were used to obtain plasma for glucose analyses and tubes with lithium heparin separator were used to obtain plasma for triglyceride, cholesterol, HDL, LDL an c-peptide analyses. The samples were centrifuged within 4 hours. Tubes with K2EDTA were used to collect full blood for HbA1c analyses. All tubes were from Greiner Bio-One, Kremsmünster, Austria
Concentrations of plasma adiponectin, IL-6 and TNF- α were measured in snap-frozen plasma. Adiponectin was measured using sandwich immunoassay, Human adiponectin Kit (MSD, Gaithersburg, MD, USA). IL-6 and TNF- α were measured using a sandwich immunoassay, Proinflammatory Panel 1 (MSD, Rockville, MD, USA). sCD14 was measured in snap-frozen plasma using an enzyme-linked immunosorbent assay (R&D, Minneapolis, USA). All assays were performed according to manufacturers’ instructions.
Insulin resistance
To measure insulin resistance, we used the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) [20]. HOMA-IR was calculated using HOMA Calculator (https://www.dtu.ox.ac.uk/ToolsSoftware/) including fasting glucose and C-peptide.
Statistics
Data were tested for normal distribution, and all soluble markers were logarithmic transformed to obtain normal distribution. Results are given as mean and 95% Confidence Interval (95% CI) or geometric mean (95% CI). Differences between groups were analyzed using one-way ANOVA followed by t test. Main outcomes and possible interactions between HIV infection and DM2 were further investigated using multivariate linear regression. The soluble markers: adiponectin, IL-6, and TNF-α were correlated to fat mass in kg to assess their correlation to fat distribution. Only significant correlations were reported. Correlations were done using Pearson correlation. Pearson chi-square test was used on categorical data. Two-tailed p-values < 0.05 were considered significant Statistical analyses were performed using SPSS version 25 (SPSS, Inc.; Chicago, IL, USA), GraphPad Prism 5 (GraphPad Software, San Diego, CA, USA) and R version 3.5.2.