From the Guidelines
The fasting blood glucose goal for a diabetic is typically between 70-130 mg/dL (3.9-7.2 mmol/L) as recommended by the most recent guidelines 1. This target range helps maintain good glycemic control while minimizing the risk of hypoglycemia. For most adults with diabetes, staying within this range before meals helps reduce the risk of long-term complications such as cardiovascular disease, neuropathy, nephropathy, and retinopathy. However, these goals may be individualized based on several factors including:
- age
- duration of diabetes
- comorbid conditions
- hypoglycemia awareness
- known CVD or advanced microvascular complications
- individual patient considerations, as suggested by previous studies 1. For elderly patients or those with multiple comorbidities, a slightly higher target (such as 100-150 mg/dL) might be appropriate to reduce hypoglycemia risk, but the latest guidelines from 2023 suggest a target range of 100-180 mg/dL (5.6-10.0 mmol/L) for noncritically ill patients with “new” hyperglycemia as well as people with known diabetes prior to admission 1. To achieve these targets, patients should adhere to their prescribed medication regimen (which may include metformin, sulfonylureas, DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 receptor agonists, or insulin), follow a consistent meal plan, engage in regular physical activity, and monitor blood glucose regularly. Morning fasting levels are particularly important as they reflect overnight glucose control and help guide medication adjustments. It is also important to note that postprandial glucose may be targeted if A1C goals are not met despite reaching preprandial glucose goals, with a target of less than 180 mg/dL (<10 mmol/L) 1.
From the Research
Fasting Blood Glucose Goals for Diabetic Patients
- The goal for fasting blood glucose (FBG) in diabetic patients is to achieve a level that corresponds to a target A1c value, with the American Diabetes Association (ADA) suggesting an equation to estimate A1c from FBG: Average Blood Glucose = A1c (%) x 28.7 - 46.7mg/dl 2.
- A study hypothesized that if patients obtain a FBG <100 mg/dl for 2-3 months, then 70% will be at an A1c goal <7.0% 2.
- Another equation to estimate A1c from FBG is (FBG+80)/30, for example, a FBG of 130mg/dl would estimate an A1c of 7.0% 2.
- The importance of achieving target FBG levels is highlighted by the fact that a drop in FBG of 28.7mg/dl is equal to a 1% drop in A1c 2.
Comparison of Therapies for Type 2 Diabetes
- Metformin is supported as first-line therapy for type 2 diabetes due to its relative safety and beneficial effects on hemoglobin A1c, weight, and cardiovascular mortality compared to sulfonylureas 3.
- The use of premixed insulin, metformin, and a glucagon-like peptide 1 receptor agonist as combination therapy for uncontrolled type 2 diabetes has shown improved glycemic control over 12 months 4.
- Trends in first-line glucose-lowering medication use among US adults with type 2 diabetes from 2019 to 2023 show a significant shift from metformin to GLP-1RAs and SGLT2is 5.
Fasting Blood Glucose Levels in Different Diseases
- A study analyzing clinical lab test results of FBG levels from healthy individuals and patients with 64 different types of diseases found that 57/64 diseases, including type 2 diabetes, had significantly increased FBG levels compared to healthy controls 6.
- The study suggests that increased FBG levels might be a general pathophysiological property of diseased tissues or organs, and that increased FBG levels might be a consequence but not the cause for either prediabetes or type 2 diabetes 6.