Characteristics of people with high visit-to-visit glycaemic variability in Type 2 diabetes

Increased visit-to-visit glycaemic variability is independently associated with adverse outcomes in Type 2 diabetes. Our aim was to identify the patient characteristics associated with raised visit-to-visit glycaemic variability in people with Type 2 diabetes.

A case-control study was conducted to establish associations between HbA_1c variability and clinical covariates in 10 130 people with Type 2 diabetes. Variability was calculated by two metrics [sd and coefficient of variation (CV)] from a minimum of four HbA_1c readings obtained over a 4-year period. High and low variability groups were defined as the top and bottom tertile of the sd or CV, and used in logistic regression analyses including a number of clinical and biochemical covariates. The analyses were stratified into low mean (< 53 mmol/mol; 7%) and high mean (≥ 53 mmol/mol; 7%) HbA_1c groups.

Findings were consistent across both HbA_1c groups and variability metrics. Treatment, independent of other factors, was the most strongly associated covariate for the risk of high HbA_1c variability. A six-fold increased risk was observed in the low HbA_1c group, between the most and least intense treatment regimens (P < 0.001). Similar findings were present in the high HbA_1c group with a three-fold increase in risk (P < 0.001). In addition, male gender, younger age, reduced HDL-cholesterol and increased BMI were all found to be independently associated with raised visit-to-visit glycaemic variability.

Intensive treatment resulting in low mean HbA_1c was associated with marked increase in HbA_1c variability. Irrespective of diabetes control, the greatest visit-to-visit variability was observed in young, insulin resistant men.