Abstract:

Objective

To explore the characteristics of glucose metabolism and influencing factors in patients with bipolar disorder （BD） comorbid with type 2 diabetes mellitus （T2DM）.

Methods

A randomized controlled study design and convenience sampling method were employed. A total of 50 hospitalized patients with BD comorbid with T2DM， who admitted to the Fifth People′s Hospital of Kaifeng from January 2024 to February 2025， were enrolled as the study group. Based on clinical subtypes of BD （BD-Ⅰ and BD-Ⅱ）， they were further divided into comorbidity group Ⅰ （n=24） and comorbidity group Ⅱ （n=26）.Concurrently， the inpatients hospitalized during the same period were recruited as the control group， subdivided into non-comorbidity group Ⅰ （n=25） and non-comorbidity group Ⅱ （n=25）. Demographic data and family history of mood disorders and/or T2DM in first-degree relatives were collected. Height， weight， waist circumference （WC）， fasting blood glucose （FBG）， fasting insulin （FINS）， and then body mass index（BMI）， homeostatic model assessment of insulin resistance （HOMA-IR）， and waist-to-height ratio（WHtR） were calculated. Cognitive function was assessed using the Montreal cognitive assessment（MoCA）. Statistical comparisons between comorbidity and non-comorbidity groups were performed using chi-square tests， t-tests， and Mann-Whitney U tests. Pearson or Spearman correlation analyses were conducted to examine associations between comorbidities and influencing factors.

Results

The comorbidity group exhibited significantly higher proportions of family history of mood disorders ［22.00%（11/50）］ and diabetes ［26.00%（13/50）］， as well as elevated WC ［（89.48±7.12）cm］， HOMA-IR（3.48±1.47），WHtR（0.53±0.05）， and FBG［（7.15±1.93）mmol/L］ compared to the non-comorbidity group ［6.00%（3/50）， 8.00%（4/50）， （85.26±8.16）cm， （2.59±1.12）， （0.51±0.05）， （5.46±0.57）mmol/L］，with statistically significant differences （χ²=5.316， 5.741， t=2.755， 3.383， 2.217， 5.943， all P＜0.05）. The comorbidity group had significantly lower scores than the non-comorbidity group on the MoCA scale in visuospatial and executive function ［2 （2， 3），3（2， 3）］， attention ［3.5（3， 4）， 4.5（4， 5）］，and total score ［18（16， 20）， 19（18， 22）］， with all differences being statistically significant （Z=-2.044， -4.105， -2.909， all P＜0.05）. No significant differences were observed in other MoCA domains（P＞0.05）. Within the comorbidity group， significant differences in WC ［（95.06±6.75）cm， （86.61±5.46）cm］， FBG［（8.19±2.29）mmol/L， （6.62±1.50）mmol/L］ and WHtR［0.56（0.53， 0.61）， 0.51（0.49， 0.54）］ were observed between patients with and without a family history of mood disorders and/or T2DM （t=-4.782， -2.905， Z=-3.687， all P＜0.05）. Correlation analysis in the comorbidity group revealed that family aggregation of mood disorders was positively associated with WC （r=0.423， P=0.002）， FBG（r=0.384， P=0.006）， WHtR（r=0.392， P=0.005）， and HOMA-IR（r=0.385， P=0.006）. Family aggregation of diabetes showed positive correlations with BMI（r=0.316， P=0.025）， FBG（r=0.305， P=0.031）， WC（r=0.548， P=0.000） and WHtR （r=0.499， P=0.000）. A significant positive association was found between family histories of diabetes and mood disorders （r=0.456， P=0.001）.

Conclusions

Patients with BD comorbid with T2DM demonstrate higher FBG， more pronounced insulin resistance， abdominal obesity， and worse cognitive function. First-degree relatives of comorbid patients should prioritize monitoring glucose metabolism and WC to mitigate the risk of mood disorders and T2DM. WHtR is recommended as a key monitoring indicator.

Key words: Bipolar disorder, Diabetes mellitus, type 2, Comorbidity, Familial aggregation, Waist-to-height ratio