Visceral obesity is a better predictor than generalized obesity for basal insulin requirement at the initiation of insulin therapy in patients with type 2 diabetes

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Abstract

Aims

Basal insulin requirement in patients with type 2 diabetes is difficult to determine because of individual variability in insulin sensitivity and secretion. We aimed to identify factors that influence basal insulin requirement in insulin-naïve patients with type 2 diabetes.

Methods

We studied 50 insulin-naïve patients with type 2 diabetes. Their basal insulin requirement was calculated by 8 h overnight intravenous insulin infusion. Patients underwent abdominal computed tomography; subcutaneous and visceral fat areas were measured.

Results

The basal insulin requirement was 31.3 ± 16.9 units/day, and it varied widely from 0.2 to 1.4 units/kg. It was positively correlated with visceral fat area (γ = 0.485, P < 0.001), body mass index (BMI, γ = 0.339, P = 0.008), glycated hemoglobin (HbA1C, γ = 0.327, P = 0.019), alanine aminotransferase (ALT, γ = 0.310, P = 0.027), and triglyceride (γ = 0.305, P = 0.032). However, body weight, waist circumference and total fat mass were not related to basal insulin requirement. Multiple linear regression analysis showed that visceral fat area, HbA1C, and ALT are independent predictors of basal insulin requirement.

Conclusions

Visceral obesity was a better predictor than generalized obesity for basal insulin requirement at the initiation of insulin therapy in patients with type 2 diabetes.

Introduction

Body weight or obesity is a commonly used determinant to assess the amount of insulin required at the initiation of insulin therapy in patients with type 2 diabetes. The initial amount of basal insulin required is known to range from 0.4 to 0.5 units/kg body weight per day [1]. However, the insulin dose determined based on body weight is frequently outside the optimal dosage range, and this may result in unexpected hypoglycemia and/or hyperglycemia [2]. Moreover, the bedtime insulin dose required to achieve reasonable glycemic control varies 20-fold, from 8 to 170 units/day [3], [4].

The insulin requirement depends on endogenous insulin secretion, insulin sensitivity, the amount of insulin absorbed, and other factors such as anti-insulin antibodies [4]. Among these, inter-individual variation in insulin sensitivity seems to be a major factor. Ryysy et al. [4] reported that hepatic fat content and insulin action on free fatty acids and glucose metabolism, rather than insulin absorption, are associated with the insulin requirement during insulin therapy in patients with type 2 diabetes. In addition, central or visceral obesity is strongly associated with insulin resistance. Hayashi et al. [5] demonstrated that visceral adiposity, not abdominal subcutaneous fat area, was associated with an increase in future insulin resistance. However, there has been no study regarding the association between visceral obesity and insulin requirement in type 2 diabetes.

In this study, we aimed to identify clinical parameters influencing inter-individual variation in basal insulin requirement in insulin-naïve patients with type 2 diabetes. To predict basal insulin requirement, we used an overnight insulin infusion algorithm with some modifications [6], [7].

Section snippets

Study subjects

Fifty consecutive patients with type 2 diabetes, in whom conventional outpatient treatment with either diet or any combination of oral antidiabetic agents had failed, were referred to the inpatient diabetes service. All study patients were hospitalized only for glycemic control. The inclusion criteria for patients in this study were age 20–75 years, a diagnosis of type 2 diabetes, poor glycemic control (glycated hemoglobin; HbA1C > 8.0% [63.9 mmol/mol]), and not on insulin therapy. The exclusion

Clinical characteristics of study subjects

The clinical characteristics of the diabetic patients are summarized in Table 2. The mean age was 56.7 ± 15.3 years, and the mean duration of diabetes was 9.0 ± 7.3 years. The mean HbA1C was 10.4 ± 1.4% (90.7 ± 15.7 mmol/mol). The mean BMI was 26.1 ± 4.8 kg/m2. Forty-one patients (82%) were treated with sulfonylurea, 33 (66%) with metformin, and 4 (8%) with thiazolidinedione. Seven patients were on diet and exercise alone.

Blood glucose changes and insulin dose administered during the 8 h overnight insulin infusion

The mean blood glucose at 22:00 h was 17.3 ± 4.9 mmol/L. The mean blood glucose

Discussion

In our study, visceral fat area was a significant predictor of basal insulin requirement at the initiation of insulin therapy in patients with type 2 diabetes. However, body weight, waist circumference, total body fat, or subcutaneous fat area were not associated with basal insulin requirement.

It is often difficult for clinicians to determine the amount of insulin required when they start insulin therapy in insulin-naïve patients with type 2 diabetes. The estimation of insulin dose based on

Conflict of interest

The authors declare that they have no conflict of interest.

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