Blood sugar, or glucose, serves as the primary energy source for the body’s cells, fueling everything from muscle movement to brain function. The body maintains glucose levels within a certain range to ensure proper functioning. When these levels are consistently too high, it can indicate a condition like diabetes. This article explores the understanding of “normal” blood sugar in 1970 and how it compares to today’s medical standards.
Blood Sugar Ranges in 1970
In 1970, the criteria for defining normal blood sugar levels and diagnosing diabetes were less refined than they are today. A fasting blood glucose level, measured after an overnight fast, was a primary indicator. While precise universal numbers for “normal” are difficult to pinpoint for that exact year, diagnostic thresholds for diabetes were generally higher.
For instance, studies and criteria from that era often considered a fasting plasma glucose level below 120 mg/dL (6.7 mmol/L) as normal. A diagnosis of diabetes might have been considered if fasting blood glucose exceeded 140 mg/dL (7.8 mmol/L) on multiple occasions. These figures reflect the medical consensus at the time.
Measurement Methods and Diagnostic Approaches Then
Measuring blood sugar in 1970 primarily involved laboratory-based chemical tests. One prominent method was the Folin-Wu method, which involved a series of chemical reactions to detect glucose. This technique precipitated proteins from the blood sample using reagents like sodium tungstate and sulfuric acid.
The glucose in the remaining filtrate would then react with alkaline copper solution, leading to a color change proportional to the glucose concentration. This method, while widely used, was known to be less specific for glucose, meaning other substances in the blood could also react and potentially lead to slightly higher readings compared to true glucose levels.
Beyond the Folin-Wu method, the 1970s marked the emergence of more accessible testing. The Ames Reflectance Meter, introduced around 1970, represented an early step towards portable glucose monitoring. This device used test strips, like the Dextrostix, which changed color based on blood glucose levels. Users would compare the strip’s color to a chart to get a semi-quantitative assessment, although these early strips and meters had limitations in precision.
How 1970 Levels Compare to Today’s Standards
The understanding of “normal” blood sugar has significantly evolved since 1970, leading to lower diagnostic thresholds for diabetes today. Current guidelines, such as those from the American Diabetes Association (ADA) and the World Health Organization (WHO), define normal fasting plasma glucose as below 100 mg/dL (5.6 mmol/L). A fasting blood glucose of 100-125 mg/dL (5.6-6.9 mmol/L) is now classified as prediabetes, indicating an increased risk. Diabetes is diagnosed when fasting plasma glucose is 126 mg/dL (7.0 mmol/L) or higher.
The 2-hour oral glucose tolerance test (OGTT) also shows a shift. A 2-hour plasma glucose level below 140 mg/dL (7.8 mmol/L) is considered normal. Prediabetes is indicated by a 2-hour value between 140-199 mg/dL (7.8-11.0 mmol/L), while 200 mg/dL (11.1 mmol/L) or higher confirms diabetes.
The HbA1c test, which measures average blood sugar over two to three months, was introduced around the mid-1970s and is now a standard diagnostic tool. A normal HbA1c is below 5.7%, with 5.7-6.4% indicating prediabetes and 6.5% or higher signaling diabetes. These updated criteria aim to identify individuals at risk earlier, allowing for interventions to prevent or delay the onset of complications.
Factors Driving Changes in Blood Sugar Understanding
Several factors have contributed to the evolution of blood sugar understanding and diagnostic criteria since 1970. Significant advancements in medical research have deepened insights into how different glucose levels impact long-term health. Large-scale studies have demonstrated that even levels previously considered “normal” can increase the risk of diabetes-related complications over time. This has led to a proactive approach, lowering thresholds to detect metabolic changes earlier.
The increasing prevalence of type 2 diabetes, often linked to lifestyle factors such as diet and reduced physical activity, has also played a role. As more people developed the condition, researchers gained a clearer picture of its progression and the benefits of early intervention. Innovations in diagnostic technology, including the development of more accurate and convenient blood glucose meters and the widespread adoption of the HbA1c test, have enabled more precise monitoring and a better understanding of glycemic control. This combination of enhanced research, changing disease patterns, and technological progress has shaped contemporary guidelines for blood sugar management.