Globally, prevalence of Diabetes mellitus has increased manifold over the years affecting nearly 589 million population worldwide. The latest International Diabetes Federation (IDF) Diabetes Atlas (2025) reports that 11.1% – or 1 in 9 – of the adult population (20-79 years) is living with diabetes, with over 4 in 10 unaware that they have the condition. Early identification of individuals at risk for type 2 diabetes mellitus (T2DM) is essential for effective prevention and timely intervention. Among the commonly used biomarkers, glycated hemoglobin (HbA1c) and insulin levels represent different aspects of glucose metabolism.
Type 2 diabetes mellitus develops gradually, often preceded by years of metabolic dysfunction. Identifying individuals during this “silent” phase is a major goal of preventive medicine. Traditionally, glucose-based parameters such as fasting plasma glucose and HbA1c have been used to diagnose and monitor diabetes. However, increasing attention has been directed toward insulin levels as earlier indicators of metabolic derangement.
This raises a clinically relevant question: Is HbA1c sufficient for predicting diabetes, or does insulin provide a better early warning?
HbA1c: A Marker of Chronic Glycaemia
HbA1c represents the percentage of haemoglobin irreversibly bound to glucose, reflecting average blood glucose levels over the preceding 8–12 weeks. It is widely used due to its convenience, standardization, and strong association with long-term microvascular complications.
Strengths of HbA1c
· Reflects long-term glycemic exposure
· Does not require fasting
· Well-validated for diagnosis and monitoring
· Strong predictor of diabetic complications
Limitations
· Rises late in the disease process
· Does not detect early insulin resistance
· Influenced by anaemia, hemoglobinopathies, pregnancy, and chronic kidney disease
· May miss high-risk individuals with normal glucose but elevated insulin
HbA1c is therefore an excellent diagnostic and prognostic marker, but not necessarily an early predictor.
Insulin Levels: A Window Into Early Metabolic Dysfunction
Insulin resistance is the hallmark of type 2 diabetes pathogenesis. In early stages, pancreatic beta cells compensate by secreting higher amounts of insulin to maintain normal glucose levels. This phase of hyperinsulinemia may persist for years before glucose or HbA1c become abnormal.
Strengths of Insulin Measurement
· Detects metabolic dysfunction before hyperglycemia
· Identifies high-risk individuals with normal HbA1c
· Reflects lifestyle-related insulin resistance (obesity, sedentary behavior)
· Useful in metabolic syndrome and prediabetes risk stratification
Limitations
· Lack of standardized reference ranges
· Significant biological variability
· Requires fasting
· Less commonly used in routine clinical practice.
Which Is the Better Predictor?
For preventive strategies, especially in younger adults, obese individuals, and those with family history of diabetes, measuring insulin levels can reveal hidden metabolic risk. Lifestyle interventions initiated during the hyperinsulinemic phase may prevent or significantly delay progression to overt diabetes.
Conversely, HbA1c remains indispensable for diagnosis, monitoring, and assessing long-term outcomes. For preventive strategies, especially in younger adults, obese individuals, and those with family history of diabetes, measuring insulin levels can reveal hidden metabolic risk. Lifestyle interventions initiated during the hyperinsulinemic phase may prevent or significantly delay progression to overt diabetes. Take away message - HbA1c and insulin are not competing markers but they are complementary tools.
Don’t you all agree with that - Prevention is always easier than treatment and by Understanding your body early, you can stay diabetes-free longer.
MBH/AB