TOPLINE: 

In a study including individuals with type 1 diabetes (T1D), type 2 diabetes (T2D), or normal glucose tolerance from the German Diabetes Study, spirometry measurements showed lower forced expiratory volume in 1 second (FEV₁) in those with T2D. These measures were linked to insulin sensitivity and insulin clearance, and Mendelian randomization supported a causal tie between the homeostasis model assessment of insulin resistance (HOMA-IR) and FEV₁.

METHODOLOGY:

• T1D and T2D vs normal glucose tolerance have been variably linked to reduced FEV₁ and forced vital capacity (FVC); however, mechanisms underlying the connection between pulmonary alterations and dysglycemia are not well understood.
• Researchers aimed to assess the association between glucose metabolism traits and changes in pulmonary function among individuals with recent-onset T1D or T2D and individuals with normal glucose tolerance. Individuals were further categorized as those with severe autoimmune diabetes, mild age-related diabetes, mild obesity-related diabetes, severe insulin-resistant diabetes, or severe insulin-deficient diabetes.
• Participants included 339 patients with T1D (mean age, 40.92 years; 426 spirometry measurements), 403 with T2D (mean age, 55.80 years; 482 spirometry measurements), and 188 control individuals (mean age, 43.77 years; 244 spirometry measurements) from the German Diabetes Study.
• Procedures comprised spirometry for the assessment of FEV₁, FVC, the Tiffeneau index, and peak expiratory flow (PEF) and metabolic phenotyping using a modified Botnia clamp — an intravenous glucose tolerance test for early insulin secretion, followed by a hyperinsulinemic-euglycemic clamp to derive whole body insulin sensitivity with space correction (M value) and insulin clearance.
• Bidirectional two-sample Mendelian randomization was used to evaluate the relationship between insulin resistance (measured using HOMA-IR, with data from the UK Household Longitudinal Study; n = 37,037) and lung function (FEV₁, FVC, and the Tiffeneau index, with data from the MAGIC study; n = 321,047) using single-nucleotide polymorphisms as instrumental variables.

TAKEAWAY:

• Individuals with T2D had a lower FEV₁ than control individuals after adjusting for confounding factors, and PEF was lower in individuals with T1D or T2D. FEV₁ and FVC were lower in participants with severe insulin-resistant diabetes, mild age-related diabetes, or mild obesity-related diabetes than in control individuals and in those with severe autoimmune diabetes.
• Both FEV₁ and FVC were associated with the M value and insulin clearance, whereas PEF was associated only with the M value. No associations were found between lung function and insulin secretion, A1c level, or fasting plasma glucose level.
• In patients with T1D, FVC was associated with insulin clearance, and PEF was associated with the M value; FEV₁ was inversely correlated with total daily insulin dose and A1c level. In those with T2D, FEV₁, FVC, and PEF were associated with the M value and insulin clearance.
• Bidirectional Mendelian randomization supported a causal association of HOMA-IR with FEV₁ (beta-coefficient, -0.13; P = .0018) and FVC (beta-coefficient, -0.11; P = .0080).

IN PRACTICE:

“Individuals with type 2 diabetes, especially the elderly and those with insulin resistance as well as individuals with type 1 diabetes who require high doses of exogenous insulin, could benefit from early screening and interventions focused on improving insulin sensitivity and reducing hyperinsulinemia to mitigate adverse pulmonary outcomes,” the authors concluded.

SOURCE:

The study was led by Maurizio Di Marco and Kalman B. Bodis, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University in Düsseldorf. It was published online in Diabetes Care.

LIMITATIONS: 

Generalizability may be limited by an ethnically nondiverse cohort and exclusion of extreme diabetes phenotypes. Despite a washout of 3 days or more, residual effects of glucose-lowering drugs could not be fully excluded. Body plethysmography and diffusion capacity data for carbon monoxide were unavailable. Cross-sectional design precluded longitudinal causal inference within the German Diabetes Study.

DISCLOSURES:

German Diabetes Study was initiated and funded by the German Diabetes Center, which is supported by the German Federal Ministry of Health and the Ministry of Culture and Science of North Rhine-Westphalia, along with German Federal Ministry of Education and Research grants to the German Center for Diabetes Research. Additional support to authors included grants from the European Community to a consortium, German Science Foundation, Schmutzler-Stiftung, and a Ministry of Culture and Science of the State of North Rhine-Westphalia initiative. One author reported receiving support from China Scholarship Council. Some authors reported receiving lecture fees; lecture, travel, and advisory honoraria; or travel support; or having advisory roles and/or other ties with various companies including Eli Lilly, Boehringer Ingelheim, and Novo Nordisk.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.