Netherlands: Higher levels of blood sugar or hyperglycemia are associated with depressive symptoms independent of lifestyle and cardiovascular risk factors, suggests a recent study in the journal Diabetologia. Further, the association between insulin resistance and depression was dependent on cardiovascular risk factors, specifically obesity.
People with type 2 diabetes are twice more likely to get depression compared to the general population. However, it is not clear whether insulin resistance and high blood sugar levels are directly involved in the etiology of depression. Therefore, Anouk F. J. Geraets, Maastricht University Medical Center (MUMC+), Maastricht, the Netherlands, and colleagues investigated the association of hyperglycemia markers and insulin resistance, measured as continuous variables, with incident depressive symptoms over 4 years of follow-up.
The researchers used data from the longitudinal population-based Maastricht Study (n = 2848; mean age 59.9 ± 8.1 years, 48.8% women, 265 incident depression cases, 10,932 person-years of follow-up). Hyperglycaemia by fasting and 2 h post-load OGTT glucose levels, HbA1c, and skin autofluorescence (reflecting AGEs) were assessed at baseline. Matsuda insulin sensitivity index and HOMA-IR was used to calculate insulin resistance at baseline.
Depressive symptoms (nine-item Patient Health Questionnaire score ≥10) were assessed at baseline and annually over 4 years. The researchers used Cox regression analyses, and adjusted for demographic, cardiovascular and lifestyle risk factors.
Key findings of the study include:
Fasting blood sugar, 2 h post-load glucose and HbA1c levels were associated with an increased risk for incident depressive symptoms after full adjustment (HR 1.20, HR 1.25, and HR 1.22 respectively)
Skin autofluorescence, insulin sensitivity index and HOMA-IR were not associated with an increased risk for incident depressive symptoms after full adjustment (HR 0.99, HR 1.02, and HR 0.93 respectively).
"These findings establish temporal association between hyperglycemia and incident depressive symptoms, supporting the concept that hyperglycemia itself is involved in the etiology of depression, and thus may provide a potential target for the prevention of depression in individuals with and without type 2 diabetes," concluded the authors.
"The association of hyperglycaemia and insulin resistance with incident depressive symptoms over 4 years of follow-up: The Maastricht Study," is published in the journal Diabetologia.
DOI: https://link.springer.com/article/10.1007/s00125-020-05247-9