The Association Between Poor Glycemic Control and Health Care Costs in People With Diabetes: A Population-Based Study

Epidemiology/Health Services Research

¹Centre d’Atenció Primària La Mina, Gerència Territorial de Barcelona, Institut Català de la Salut, Barcelona, Spain
²DAP-Cat Group, Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la Recerca a l’Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
³CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Barcelona, Spain
⁴Department of Economic Analysis and Finance, Faculty of Law and Social Sciences, University of Castilla-La Mancha, Toledo, Spain
⁵Department of Endocrinology and Nutrition, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
⁶Centre d’Atenció Primària Raval Sud, Gerència Territorial de Barcelona, Institut Català de la Salut, Barcelona, Spain

Corresponding authors: Josep Franch-Nadal, josep.franch{at}gmail.com, and Didac Mauricio, didacmauricio{at}gmail.com

Diabetes Care 2020 Apr; 43(4): 751-758. https://doi.org/10.2337/dc19-0573

Article Figures & Tables

Table 1

Mean per patient annual direct medical costs (in 2011 €)

	Patients with HbA_1c (N = 100,391)	HbA_1c <7% (N = 54,395)	7% ≥ HbA_1c < 8% (N = 24,994)	8% ≥ HbA_1c < 10% (N = 16,286)	HbA_1c ≥10% (N = 4,716)	Patients without HbA_1c (N = 26,419)
Total costs	3,038.76 (6,580.76)	2,842.95 (6,233.06)	3,102.32 (7,292.54)	3,504.30 (6,548.69)	3,352.77 (6,520.38)	3,381.14 (12,049.61)
Consultations with GP	607.52 (553.98)	585.24 (540.96)	620.52 (549.74)	654.01 (581.80)	635.16 (610.29)	460.94 (548.53)
Hospitalization	1,203.58 (6,082.86)	1,131.46 (5,705.22)	1,197.99 (6,865.55)	1,396.55 (6,041.79)	1,398.63 (6,012.60)	1,681.00 (11,214)
Referrals to specialist care	123.59 (164.85)	119.45 (160.32)	126.83 (164.75)	131.76 (177.93)	125.88 (168.44)	81.58 (142.35)
Tests	14.72 (39.39)	14.44 (38.87)	15.66 (40.85)	14.45 (38.68)	13.94 (39.48)	9.76 (33.82)
Self-monitoring test strips	49.95 (11.72)	49.89 (11.63)	50.23 (11.90)	49.85 (11.76)	49.44 (11.64)	50.46 (12.03)
Medications	930.07 (986.09)	825.59 (938.43)	989.08 (999.08)	1,154.61 (1,052.55)	1,046.94 (1,046.14)	905.79 (1,276.16)
Dialysis	34.16 (949.78)	43.44 (1,076.27)	23.53 (773.46)	25.90 (822.35)	11.91 (578.20)	147.49 (1,982.07)

Table 2

Results from the GLM regression with γ distribution and identity link on total costs

Variables	Model 1	Model 2
Diabetes duration categories (reference: 0–2 years)
2–5 years	162.6^*** (44.74)	127.9^*** (41.71)
5–10 years	520.2^*** (48.19)	347.9^*** (43.78)
>10 years	1,039^*** (66.19)	738.7^*** (60.68)
HbA_1c categories (reference: HbA_1c <7%)
7% ≥ HbA_1c < 8%	147.8^*** (42.21)	127.5^*** (39.11)
8% ≥ HbA_1c < 10%	527.0^*** (58.04)	395.1^*** (52.64)
HbA_1c ≥10%	582.3^*** (95.64)	428.3^*** (86.16)
Complications (reference: no complications)
Macrovascular complications		1,516^*** (97.51)
Microvascular complications		844.1^*** (69.74)
Both types		2,091^*** (83.61)
Observations (n)^a	90,874	90,874
AIC	17.947	17.892
BIC	−1,001,518	−1,006,790
Log-likelihood	−866,376.45	−863,723.18

Cost in 2011 €, with SEs given in parentheses. Model 1 adjusted for age (in categories), sex, BMI (in categories), hypertension and hypercholesterolemia, and smoking habits. Model 2 adds to model 1 whether the individual has any micro- or macrovascular complications or both. Reference categories: diabetes duration of <2 years, HbA_1c <7% (models 1 and 2), and no vascular complications (model 2).
AIC, Akaike information criterion; BIC, Bayesian information criterion.
↵*** P < 0.01.
↵a Only individuals with complete data for all lifestyle factors (and any other variable included in the regressions) were included in the analyses (i.e., 90,874 patients in both models 1 and 2 out of 100,391 patients from the whole patient cohort).

Table 3

Results from the two-part model on hospitalization costs

Variables	First-part probit of two-part model, model 1^†	Second-part GLM with γ distribution and identity link of two-part model, model 1^‡	First-part probit of two-part model, model 2^†	Second-part GLM with γ distribution and identity link of two-part model, model 2^‡
Diabetes duration categories (reference: 0–2 years)
2–5 years	0.0529^*** (0.0177)	147.6 (369.3)	0.0462^*** (0.0178)	106.1 (362.0)
5–10 years	0.100^*** (0.0161)	773.4^** (339.1)	0.0791^*** (0.0162)	568.3^* (333.2)
>10 years	0.191^*** (0.0175)	1,215^*** (373.7)	0.151^*** (0.0177)	910.9^** (371.1)
HbA_1c categories (reference: HbA_1c <7%)
7% ≥ HbA_1c < 8%	0.0103 (0.0124)	109.9 (268.4)	−0.000905 (0.0124)	87.46 (262.6)
8% ≥ HbA_1c < 10%	0.0793^*** (0.0144)	927.5^*** (330.3)	0.0500^*** (0.0146)	811.1^** (323.6)
HbA_1c ≥10%	0.169^*** (0.0243)	843.6 (552.1)	0.126^*** (0.0246)	636.8 (541.8)
Complications (reference: no complications)
Macrovascular complications			0.297^*** (0.0173)	1,733^*** (388.8)
Microvascular complications			0.201^*** (0.0162)	974.5^*** (357.5)
Both types			0.358^*** (0.0138)	2,323^*** (320.1)
Constant	−1.688^*** (0.0369)	4,521^*** (693.5)	−1.677^*** (0.0370)	4,404^*** (690.8)
Observations (n)	90,874	13,837	90,874	13,837
AIC		20.06		20.04
BIC		−117,709.7		−117,854.6
Log-likelihood	−38,835.91	−138,739.50	−38,424.52	−138,652.77

Model 1 adjusted for age (in categories), sex, BMI (in categories), hypertension and hypercholesterolemia, and smoking habits. Model 2 adds to model 1 whether the individual has any micro- or macrovascular complications or both. Reference categories: diabetes duration of <2 years, HbA_1c <7% (models 1 and 2), and no vascular complications (model 2).
AIC, Akaike information criterion; BIC, Bayesian information criterion.
↵† The coefficient denotes probability (e.g., 0.0529 has to be interpreted as a 5.29% increase in the probability of being admitted to hospital). SEs are given in parentheses.
↵‡ Costs in 2011 €, with SEs given in parentheses.
↵* P < 0.1;
↵** P < 0.05;
↵*** P < 0.01.

Table 4

Results from the GLM regression with γ distribution and log link on treatment costs

Variables	Model 1^†	Model 2^†
Diabetes duration categories (reference: 0–2 years)
2–5 years	0.148^*** (0.0122)	0.140^*** (0.0122)
5–10 years	0.313^*** (0.0112)	0.284^*** (0.0112)
>10 years	0.430^*** (0.0125)	0.375^*** (0.0126)
HbA_1c categories (reference: HbA_1c <7%)
7% ≥ HbA_1c < 8%	0.132^*** (0.00907)	0.119^*** (0.00908)
8% ≥ HbA_1c < 10%	0.308^*** (0.0107)	0.275^*** (0.0108)
HbA_1c ≥10%	0.336^*** (0.0182)	0.281^*** (0.0183)
Complications (reference: no complications)
Macrovascular complications		0.384^*** (0.0135)
Microvascular complications		0.270^*** (0.0121)
Both types		0.552^*** (0.0107)
Observations (n)	90,874	90,874
AIC	15.56	15.52
BIC	−1,012,478	−1,016,589
Log-likelihood	−751,214.62	−749,055.06

Model 1 adjusted for age (in categories), sex, BMI (in categories), hypertension and hypercholesterolemia, and smoking habits. Model 2 adds to model 1 whether the individual has any micro- or macrovascular complications or both. Reference categories: diabetes duration of <2 years, HbA_1c <7% (models 1 and 2), and no vascular complications (model 2).
AIC, Akaike information criterion; BIC, Bayesian information criterion.
↵† The coefficient denotes probability (e.g., 0.148 has to be interpreted as a 14.8% increase in treatment costs). SEs are given in parentheses.
↵*** P < 0.01.