Factors that determine glucose variability, defined by the coefficient of variation in continuous glucose monitoring values, in a Chinese population with type 2 diabetes

Abstract Aims To elucidate the clinical determinants of the coefficient of variation (CV) of glucose by analysing the pancreatic β‐cell function of subjects with type 2 diabetes mellitus (T2DM). Methods A total of 716 Chinese subjects with T2DM were included. Continuous glucose monitoring (CGM) was used to assess blood glucose, and the CV was calculated. C‐peptide concentration at 0, 0.5, 1, 2 and 3 hours (Cp0h, Cp0.5h, Cp1h, Cp2h and Cp3h, respectively) was measured after a standard 100‐g steamed bun meal test to assess pancreatic β‐cell function. The determinants of glucose variability defined by the CV of CGM values were explored from two perspectives: the CV of qualitative variables and the CV of quantitative variables. Results Our data revealed that C‐peptide concentration (Cp0h, Cp0.5h, Cp1h, Cp2h, Cp3h), area under the curve for C‐peptide concentration at 0.5 and 3 hours (AUC‐Cp0.5h and AUC‐Cp3h) decreased with increasing CV quartile ( P < 0.05). The CV was negatively correlated with homeostatic model assessment of β‐cell function index, C‐peptide concentration at all timepoints, and AUC‐Cp0.5h and AUC‐Cp3h ( P < 0.001). Quantile regression analysis showed that AUC‐Cp0.5h had an overall negative effect on the CV in the 0.05 to 0.95 quartiles, and AUC‐Cp3h tended to have a negative effect on the CV in the 0.2 to 0.65 quartiles. After adjusting for confounders, multinomial logistic regression showed that each 1‐unit increase in AUC‐Cp0.5h was associated with a 31.7% reduction in the risk of unstable glucose homeostasis (CV > 36%; P = 0.036; odds ratio 0.683; 95% confidence interval 0.478‐0.976). We also identified the AUC‐Cp0.5h (0.735 ng/mL) and AUC‐Cp3h (13.355 ng/mL) cut‐off values for predicting unstable glucose homeostasis (CV >36%) in T2DM subjects. Conclusion Our study suggests that impaired pancreatic β‐cell function may be a clinical determining factor of CV of glucose in people with T2DM.