Glycaemic Variability and C‐Peptide in Bangladeshi Children, Adolescents, and Young Adults With Diabetes: A Prospective Study

OBJECTIVES: To characterise the magnitude of glycaemic variability and to examine the factors associated with it, with particular attention to residual beta-cell function measured by fasting C-peptide, in children, adolescents, and young adults with diabetes in Bangladesh. DESIGN AND SETTING: Prospective observational study at the BADAS Paediatric Diabetes Care and Research Centre, BIRDEM, Dhaka, using 14 days of blinded professional continuous glucose monitoring (CGM). Participants were enrolled between March and November 2024. PARTICIPANTS: Ninety-seven participants aged 1-25 years (68 with Type 1 and 29 with Type 2 diabetes) had at least seven valid CGM days and a paired HbA1c within 2 weeks of CGM initiation. Fasting C-peptide was available for 46 participants. MAIN OUTCOME MEASURES: The coefficient of variation (CV) of glucose as the primary metric of variability; time in range, time above range, and time below range as secondary metrics; and independent predictors of CV on multivariable regression. RESULTS: Mean CV was 39.4% (SD 9.2), and 59 of 97 participants (60.8%) were at or above the recommended target of 36%. CV was higher in Type 1 than Type 2 diabetes (41.9% vs. 33.3%). Lower fasting C-peptide was independently associated with higher CV after adjustment for diabetes type, age, and insulin dose (-1.94 percentage points per ng/mL, 95% CI -3.35 to -0.53; model R-squared 0.52), with a graded relationship across pre-specified C-peptide categories for CV, time in range, and time below range. CONCLUSIONS: Glycaemic variability substantially exceeds international targets in this setting. Fasting C-peptide, available for fewer than half of the cohort, showed a graded association with variability that is best regarded as hypothesis-generating; if confirmed in larger studies, it could offer a low-cost means of identifying children at highest variability risk where CGM access is limited.