Prevalence of pre-diabetes and type 2 diabetes mellitus among Sami and non-Sami men and women in Northern Norway – The SAMINOR 2 Clinical Survey

Abstract

The aim of this study was to determine and compare the prevalence of pre-diabetes and type 2 diabetes mellitus (T2DM) among Sami and non-Sami men and women of rural districts in Northern Norway. The SAMINOR 2 Clinical Survey is a cross-sectional population-based study performed in 2012–2014 in 10 municipalities of Northern Norway. A total of 12,455 Sami and non-Sami inhabitants aged 40–79 years were invited to participate and 5878 were included in the analyses. Participants with self-reported T2DM and/or a glycated haemoglobin (HbA1c) result ≥6.5% were categorised as having T2DM. Those with 5.7%≤HbA1c<6.5% were categorised as pre-diabetics. In men, the total age-standardised prevalence of pre-diabetes (37.9% vs 31.4%) and T2DM (10.8% vs 9.5%) were higher in Sami compared with non-Sami; the ethnic difference was statistically significant for both pre-diabetes (OR 1.42, p < 0.001) and T2DM (OR 1.31, p = 0.042). In women, pre-diabetes (36.4% vs 33.5%) and T2DM (8.6% vs 7.0%) were also more common in Sami than non-Sami; the differences in both pre-diabetes (OR 1.20, p = 0.025) and T2DM (OR 1.38, p = 0.021) were also statistically significant. The observed ethnic difference in the waist-to-height ratio (WHtR) was a plausible explanation for the ethnic difference in the prevalence of pre-diabetes and T2DM.

Relationships between metabolic markers and obesity measures in two populations that differ in stature—The SAMINOR Study

“…The Sami is an ethnic minority and indigenous people living mainly in the northern parts of Norway, Sweden, and Finland and on the Kola Peninsula in Russia. In the last four decades, research from Norway has shown variations in obesity levels between people with and without Sami affiliation . Sami women have repeatedly been shown to have higher BMI and/or larger WC than non‐Sami women .…”

“…In the last four decades, research from Norway has shown variations in obesity levels between people with and without Sami affiliation . Sami women have repeatedly been shown to have higher BMI and/or larger WC than non‐Sami women . Yet researchers have observed differences concerning diabetes mellitus (DM) prevalence comparing the two groups with lower risks of DM in Sami than in non‐Sami women in 1974–1975, similar in 2003–2004, and higher in 2012–2014 .…”

“…Sami women have repeatedly been shown to have higher BMI and/or larger WC than non‐Sami women . Yet researchers have observed differences concerning diabetes mellitus (DM) prevalence comparing the two groups with lower risks of DM in Sami than in non‐Sami women in 1974–1975, similar in 2003–2004, and higher in 2012–2014 . In contrast, Sami men have previously been shown to have a lower WC than non‐Sami men, although recent reports show that Sami men have a higher prevalence of DM and a higher severity score of metabolic syndrome (MetS) than non‐Sami men .…”

“…As cut‐offs for obesity should be population specific, researchers have questioned the need for ethnic‐specific cut‐offs in Northern Norway . On average, Sami populations have lower statures than non‐Sami Norwegian populations . Short people with a given WC are likely to be relatively fatter and have higher metabolic risk than tall people with the same WC .…”

Estimated 8-year cumulative incidence of diabetes mellitus among Sami and non-Sami inhabitants of Northern Norway - The SAMINOR Study

“…Previous research based on data from 24 municipalities in the SAMINOR 1 Survey (2003–2004), showed no statistically significant difference between Sami and non-Sami in the prevalence of DM, defined by self-report and/or non-fasting plasma glucose ≥11.1 mmol/L [8, 9]. However, a study using data from the SAMINOR 2 Clinical Survey (2012–2014), found higher prevalence of both pre-diabetes and type 2 DM among Sami people, when self-report and/or HbA1c ≥ 6.5% was used to define diabetes cases [10]. However, due to the different population samples and diagnostic methods applied, it is not possible to ascertain whether the higher diabetes prevalence in SAMINOR 2 among Sami participants reflects a higher incidence of diabetes over the last decade.…”