From the Guidelines
Normal serum insulin levels differ significantly between Type 1 and Type 2 diabetics, with Type 1 diabetics typically having very low or undetectable insulin levels and Type 2 diabetics often having normal or elevated insulin levels, especially in the early stages of the disease. In Type 1 diabetes, insulin levels are typically very low or undetectable because the pancreatic beta cells have been destroyed by an autoimmune process, resulting in little to no endogenous insulin production, as noted in the context of diabetes diagnosis and management 1. These patients require exogenous insulin therapy for survival. In contrast, Type 2 diabetics often have normal or elevated insulin levels, especially in the early stages of the disease, due to insulin resistance, as discussed in the management of hyperglycemia in Type 2 diabetes 1. Their bodies produce insulin but cannot use it effectively, leading to compensatory hyperinsulinemia. As Type 2 diabetes progresses, insulin production may decline as beta cells become exhausted, but levels typically remain higher than in Type 1 diabetes. This fundamental difference explains why Type 1 diabetics always need insulin therapy, while Type 2 diabetics may initially be managed with lifestyle modifications and oral medications that improve insulin sensitivity or enhance insulin secretion. Measuring C-peptide levels can help differentiate between these types, as C-peptide is produced in equal amounts to endogenous insulin and will be low in Type 1 but normal or high in early Type 2 diabetes. Key factors to consider in managing Type 2 diabetes include the use of medications that do not increase body weight, such as SGLT2 inhibitors, which can be added to insulin regimens to lower blood glucose levels without increasing insulin doses, weight gain, or hypoglycemia, as supported by recent evidence 1. Overall, understanding the differences in insulin levels and pathophysiology between Type 1 and Type 2 diabetes is crucial for effective management and treatment of these conditions. Some of the key points to consider include:
- The distinction between Type 1 and Type 2 diabetes in terms of insulin production and resistance
- The role of C-peptide levels in differentiating between Type 1 and Type 2 diabetes
- The importance of using medications that do not increase body weight in managing Type 2 diabetes
- The potential benefits of combining insulin with glucose-lowering medications, such as SGLT2 inhibitors, in Type 2 diabetes management.
From the Research
Normal Serum Insulin Levels
The normal serum insulin levels for Type 2 and Type 1 diabetics are not explicitly stated in the provided studies. However, the following information can be gathered:
- Insulin therapy is the primary treatment for Type 1 diabetes mellitus (T1DM) 2
- For Type 2 diabetes mellitus (T2DM), insulin is considered when HbA1c is ≥ 7.5% (≥ 58 mmol/mol) and is essential for treatment when HbA1c ≥ 10% (≥ 86 mmol/mol) 2
- The target glycated hemoglobin A1c (HbA1c) for all children with T1DM is recommended to be < 7.5% (< 58 mmol/mol) 2
Insulin Therapy
Some key points about insulin therapy are:
- Insulin preparations are characterized by the onset of the insulin action, the peak profile, and duration of action 3
- Available insulin preparations include short-acting, long-acting, and premixed preparations of human insulin, and insulin analogues 3
- The gold standard of insulin therapy in T1DM is functional insulin therapy with a basal-bolus insulin regimen and control and adaptation of the therapy by the patient 3
- Various insulin regimens are available for treating patients with T2DM, including basal insulin-supported oral therapy, supplementary mealtime injection of short-acting insulin or insulin analogues, conventional insulin therapy, or a basal-bolus procedure 3
Combination Therapy
The following information is available on combination therapy:
- Most patients with T2DM will need incrementally more complex therapeutic regimens to control hyperglycemia as the disease progresses 4
- Adding other antidiabetes medications to insulin can improve glycemic control and potentially lower the required insulin dose, resulting in less weight gain and lower risk for hypoglycemia 4
- GLP-1 receptor agonists, DPP-4 inhibitors, and SGLT2 inhibitors improve glycemic control when added to insulin and have a low propensity for hypoglycemia and cause no change (DPP-4 inhibitors) or a reduction (GLP-1 receptor agonists, SGLT2 inhibitors) in body weight 4