Distribution and drivers of costs in type 2 diabetes mellitus treated with oral hypoglycemic agents: a retrospective claims data analysis

Figures & data

Table 1. Distribution of all-cause and diabetes-related costs among type 2 diabetes patients with oral hypoglycemic agent and lab test usage.

	Distribution of costs across the 4104 patients in the study sample				Patients incurring 80% of the costs*
Cost components	Share of total costs, %	Share of patients incurring costs, %	Mean cost (SD), $	Median cost (IQR), $	Number of patients, n	Share of all patients, %
All-cause costs^†
Pharmacy	36.3	100	4913 (5042)	3822 (2024–6372)	2071	50.5
Hypoglycemic agent	13.7	100	1855 (1922)	1469 (223–2751)	1658	40.4
Other pharmacy	22.6	99	3058 (4387)	2082 (937–3767)	1816	44.2
Medical	63.7	100	8635 (21670)	2431 (1016–6933)	963	23.5
IP	23.1	11	3132 (14990)	0 (0–0)	190	4.6
ER	1.4	15	195 (927)	0 (0–0)	256	6.2
OP	34.0	99	4610 (11133)	1953 (890–4599)	1347	32.8
Other medical services	5.2	51	698 (5073)	24 (0–338)	454	11.1
Total	–	100	13,548 (23260)	7389 (4188–13714)	1728	42.1
Diabetes-related costs^‡
Pharmacy (hypoglycemic agent)	40.5	100	1855 (1922)	1469 (223–2751)	1658	40.4
Medical	59.5	99	2728 (10187)	620 (384–1149)	604	14.7
IP	29.9	7	1370 (8873)	0 (0–0)	112	2.76
ER	1.7	7	76 (430)	0 (0–0)	127	3.1
OP	25.1	97	1151 (3404)	530 (310–874)	1481	36.1
Other medical services	2.9	35	131 (658)	0 (0–68)	330	8.0
Total	–	100	4583 (10449)	2546 (961–4361)	1558	38.0

ER, emergency room; IQR, interquartile range from Q1–Q3; IP, inpatient; OP, outpatient; SD, standard deviation.

*Costs incurred by patients were added in descending order (i.e., starting from the patient with highest costs) until the 80% cost cut-off was reached.

†All-cause costs were defined as the sum of all costs for medical services and medications, regardless of diagnosis or type of medication.

‡Diabetes-related costs were defined as the sum of claims for a medical service associated with a diagnosis for diabetes (i.e., ICD-9 CM codes 250.x) or claims for a hypoglycemic agent.

Table 2. Characteristics of study population: comparison high all-cause cost cohort vs lower all-cause cost cohort.

Characteristics	High cost cohort (n = 1026)	Lower cost cohort (n = 3078)	p-Value*
Demographics at index date
Age, Mean (SD)	55.3 (8.0)	53.4 (8.5)	<0.001†
Female, n (%)	480 (46.8)	1264 (41.1)	0.001†
Region, n (%)
Northeast	129 (12.6)	349 (11.3)	0.286
North Central	236 (23.0)	593 (19.3)	0.010†
South	552 (53.8)	1841 (59.8)	<0.001†
West	109 (10.6)	293 (9.5)	0.303
Insurance plan type, n (%)
Comprehensive	64 (6.2)	134 (4.4)	0.015†
Non-Capitated Point-of-Service (POS)	200 (19.5)	652 (21.2)	0.248
Preferred Provider Organization (PPO)	710 (69.2)	2160 (70.2)	0.555
Consumer-Driven Health Plan (CDHP)	39 (3.8)	102 (3.3)	0.458
High Deductible Health Plan (HDHP)	10 (1.0)	20 (0.6)	0.290
Hypoglycemic agents used during the 1-year study period
Hypoglycemic Agents, n (%)
Alpha-Glucosidase Inhibitors	11 (1.1)	27 (0.9)	0.572
Hypoglycemic Agents - Amylin Analogs	7 (0.7)	6 (0.2)	0.016†
Hypoglycemic Agent Combinations	225 (21.9)	818 (26.6)	0.003†
Biguanide Sensitizers	681 (66.4)	2126 (69.1)	0.108
Dipeptidyl Peptidase-4 (DPP-4) Inhibitors	198 (19.3)	505 (16.4)	0.033†
Human Insulin	420 (40.9)	562 (18.3)	<0.001†
Incretin Mimetic Agents (GLP-1 Receptor Agonists)	170 (16.6)	260 (8.4)	<0.001†
Meglitinide Analogues	22 (2.1)	50 (1.6)	0.272
Sulfonylureas	440 (42.9)	1216 (39.5)	0.056
Thiazolidinediones (TZDs)	318 (31.0)	900 (29.2)	0.287
Other	38 (3.7)	46 (1.5)	<0.001†
Number of different hypoglycemic drug classes, Mean (SD)	3.0 (1.3)	1.8 (0.9)	<0.001†
At least 2 different hypoglycemic drug classes, n (%)	905 (88.2)	581 (56.6)	<0.001†
At least 3 different hypoglycemic drug classes, n (%)	631 (61.5)	200 (19.5)	<0.001†
Use of hypoglycemic agents
Treatment gaps ≥90 consecutive days, n (%)	113 (11.0)	387 (12.6)	0.186
Proportion of days of use during the period, Mean (SD)	85.2 (20.0)	82.7 (20.9)	<0.001†
Used hypoglycemic agents for more than 80% of the period, n (%)	771 (75.1)	2173 (70.6)	0.005†
Use of bile acid sequestrants	32 (3.1)	47 (1.5)	<0.001†
HbA1c lab test results
Within glycemic goal (i.e., HbA1c level <7% NGSP [<53 mmol/mol IFFC]) at the index date, n (%)	479 (46.7)	1471 (47.8)	0.539
Average HbA1c level during the 1-year study period, Mean (SD)
In % NGSP units	7.3 (1.3)	7.2 (1.2)	0.354
In mmol/mol IFCC units	56 (14.2)	55 (13.1)
Percentage of time within glycemic goal during the 1-year study period (i.e., HbA1c level <7%), Mean (SD)	49.7 (43.2)	50.6 (43.1)	0.464
Complications of diabetes identified during the 1-year study period
Microvascular complications
Diabetic retinopathy	161 (15.7)	292 (9.5)	<0.001†
Nephropathy	173 (16.9)	206 (6.7)	<0.001†
Neuropathy	239 (23.3)	279 (9.1)	<0.001†
Macrovascular complications
Atherosclerosis, aneurysm, or embolism	70 (6.8)	63 (2.0)	<0.001†
Peripheral vascular conditions	150 (14.6)	153 (5.0)	<0.001†
Cerebrovascular disease	113 (11.0)	87 (2.8)	<0.001†
Coronary artery disease	305 (29.7)	235 (7.6)	<0.001†
Non-vascular complications
Infections	241 (23.5)	386 (12.5)	<0.001†
Other ocular complications	247 (24.1)	452 (14.7)	<0.001†
Ulceration or diabetic bone changes	49 (4.8)	31 (1.0)	<0.001†
Ketoacidosis or hyperosmolarity	12 (1.2)	12 (0.4)	0.005†
Hypoglycemia	70 (6.8)	48 (1.6)	<0.001†
Diabetic coma	7 (0.7)	25 (0.8)	0.682
Unspecified diabetes-related complication	78 (7.6)	120 (3.9)	<0.001†
Health resource utilization during the 1-year study period
IP admission related to a complication, n (%)	208 (20.3)	20 (0.6)	<0.001†
ER visit related to a complication, n (%)	49 (4.8)	30 (1.0)	<0.001†
Patients seen by an endocrinologist, n (%)	195 (19.0)	353 (11.5)	<0.001†
Comorbidity profile measured during the 1-year study period
Charlson comorbidity index (without diabetes), Mean (SD)	1.3 (1.7)	0.3 (0.7)	<0.001†
Comorbidity associated with diabetes
Hypertension and associated conditions	679 (66.2)	1709 (55.5)	<0.001†
Lipid disorders	723 (70.5)	2106 (68.4)	0.220
Congestive heart failure	85 (8.3)	34 (1.1)	<0.001†
Overweight, obesity	109 (10.6)	151 (4.9)	<0.001†
Mental disorder	117 (11.4)	109 (3.5)	<0.001†
Other genitourinary system disorder	248 (24.2)	301 (9.8)	<0.001†
Other (physical or mental) comorbid conditions
AIDS	10 (1.0)	0 (0.0)	–
Anemia	184 (17.9)	180 (5.8)	<0.001†
Chronic pulmonary disease	154 (15.0)	200 (6.5)	<0.001†
Coagulopathy	36 (3.5)	20 (0.6)	<0.001†
Fluid electrolyte disorders	98 (9.6)	59 (1.9)	<0.001†
Hypothyroidism	189 (18.4)	336 (10.9)	<0.001†
Liver disease	76 (7.4)	43 (1.4)	<0.001†
Cancer	134 (13.1)	88 (2.9)	<0.001†
Other neurological disorders	58 (5.7)	27 (0.9)	<0.001†
Paralysis	6 (0.6)	3 (0.1)	0.004†
Psychoses	90 (8.8)	60 (1.9)	<0.001†
Pulmonary circulation disorders	27 (2.6)	9 (0.3)	<0.001†
Rheumatoid arthritis	68 (6.6)	41 (1.3)	<0.001†
Valvular disease	50 (4.9)	61 (2.0)	<0.001†
Behavioral factors
Alcohol abuse	2 (0.2)	4 (0.1)	0.637
Drug abuse	4 (0.4)	5 (0.2)	0.177
Smoker	16 (1.6)	24 (0.8)	0.028†
Weight loss	20 (1.9)	14 (0.5)	<0.001†

AIDS, acquired immune deficiency syndrome; ER, emergency room; HbA1c, glycated hemoglobin; IFFC, International Federation of Clinical Chemistry; IP, inpatient; n, number; NGSP, National Glycohemoglobin Standardization Program; SD, standard deviation.

*Comparing high and lower cost cohorts using chi-square or Fisher tests for categorical variables and t-tests for continuous variables.

†Differences between the high and lower cost cohorts were statistically significant at p < 0.05.

Table 3. All-cause and diabetes-related high cost drivers among type 2 diabetes patients receiving OHAs.

Potential cost drivers*	All-cause costs		Diabetes-related costs
	OR (95% CI)	p-Value	OR (95% CI)	p-Value
Demographics at index date
Age (per year increase)	1.00 (0.99;1.01)	0.772	0.99 (0.98;1.00)	0.026†
Female (vs Male)	1.06 (0.88;1.29)	0.518	0.81 (0.67;0.97)	0.025†
Region
Northeast	1.14 (0.85;1.52)	0.380	0.77 (0.56;1.03)	0.085
North Central	1.26 (0.98;1.60)	0.066	1.33 (1.05;1.68)	0.019†
South (Reference group)	1	–	1	–
West	1.23 (0.90;1.67)	0.189	0.92 (0.67;1.25)	0.582
Insurance Plan Type
Non-Capitated Point-of-Service (POS)	0.81 (0.56;1.17)	0.259	0.74 (0.51;1.09)	0.125
Preferred Provider Organization (PPO)	0.78 (0.57;1.08)	0.128	1.15 (0.83;1.61)	0.397
Other plans^‡ (Reference group)	1	–	1	–
Hypoglycemic agent use during the 1-year study period
Hypoglycemic agents
Human Insulin	2.42 (1.93;3.03)	<0.001†	3.15 (2.59;3.85)	<0.001†
Number of hypoglycemic drug class used	1.16 (1.07;1.26)	<0.001†	1.68 (1.55;1.82)	<0.001†
Use of hypoglycemic agents
Proportion of days of use during the study period (per 1% increase)	1.01 (1.00;1.01)	0.026†	1.02 (1.02;1.03)	<0.001†
Use of bile acid sequestrants	1.29 (0.71;2.28)	0.386	0.99 (0.55;1.74)	0.970
Lab test information
Percentage of time within glycemic goal during the study period
<3 months	0.73 (0.57;0.94)	0.016†	1.05 (0.83;1.33)	0.673
3–9 months (Reference group)	1	–	1	–
≥9 months	1.11 (0.86;1.42)	0.430	0.93 (0.73;1.20)	0.573
Complications of diabetes identified during the 1-year study period
Microvascular complications
Diabetic retinopathy	1.06 (0.80;1.40)	0.667	1.17 (0.90;1.51)	0.237
Nephropathy	1.30 (0.96;1.73)	0.085	1.23 (0.92;1.64)	0.161
Neuropathy	1.72 (1.34;2.20)	<0.001†	1.50 (1.17;1.92)	0.001†
Macrovascular complications
Atherosclerosis, aneurysm, or embolism	2.01 (1.24;3.22)	0.004†	1.42 (0.86;2.32)	0.169
Peripheral vascular conditions	1.17 (0.83;1.64)	0.354	1.21 (0.87;1.67)	0.254
Cerebrovascular disease	1.48 (0.99;2.20)	0.055	0.74 (0.49;1.13)	0.171
Coronary artery disease	2.83 (2.19;3.65)	<0.001†	1.56 (1.20;2.03)	<0.001†
Non-vascular complications
Infections	0.89 (0.67;1.19)	0.443	0.93 (0.70;1.24)	0.638
Other ocular complications	1.34 (1.06;1.69)	0.012†	1.54 (1.23;1.93)	<0.001†
Ulceration or diabetic bone changes	1.25 (0.65;2.37)	0.497	1.83 (0.99;3.42)	0.056
Ketoacidosis or hyperosmolarity	1.91 (0.61;5.62)	0.252	0.88 (0.25;2.96)	0.842
Hypoglycemia	1.46 (0.84;2.51)	0.177	1.69 (1.01;2.85)	0.046†
Diabetic coma	0.37 (0.10;1.14)	0.112	0.52 (0.18;1.36)	0.201
Unspecified diabetes-related complication	1.25 (0.83;1.86)	0.275	1.08 (0.73;1.59)	0.682
Healthcare utilization during the 1-year study period
Any IP admission related to a complication	13.54 (8.14;23.57)	<0.001†	9.69 (6.31;15.08)	<0.001†
Any ER visit related to a complication	1.90 (1.01;3.59)	0.047†	2.33 (1.28;4.23)	0.006†
Patient seen by an endocrinologist	1.23 (0.96;1.59)	0.105	1.91 (1.51;2.42)	<0.001†
Comorbidity profile measured during the 1-year study period
Comorbidity associated with diabetes
Hypertension and associates condition	1.20 (1.00;1.45)	0.052	1.07 (0.89;1.28)	0.477
Lipid disorders	1.16 (0.95;1.42)	0.150	1.28 (1.05;1.57)	0.016†
Congestive heart failure	1.69 (0.97;2.96)	0.065	0.62 (0.37;1.03)	0.070
Overweight, obesity	1.76 (1.25;2.46)	0.001†	1.75 (1.24;2.46)	0.001†
Mental disorder	2.39 (1.55;3.66)	<0.001†	1.36 (0.86;2.13)	0.188
Other genitourinary system disorder	2.04 (1.52;2.74)	<0.001†	1.55 (1.15;2.09)	0.004†
Other (physical or mental) comorbid conditions
AIDS	–	–	0.42 (0.07;2.21)	0.317
Anemias (blood loss or deficiency)	1.61 (1.20;2.16)	0.002†	1.16 (0.85;1.56)	0.348
Chronic Pulmonary Disease	1.72 (1.28;2.32)	<0.001†	1.03 (0.75;1.40)	0.868
Coagulopathy	1.67 (0.79;3.53)	0.176	0.85 (0.40;1.74)	0.672
Fluid Electrolyte Disorders	2.59 (1.66;4.02)	<0.001†	1.56 (1.02;2.38)	0.039†
Hypothyroidism	1.49 (1.16;1.92)	0.002†	0.98 (0.75;1.28)	0.898
Liver Disease	5.35 (3.37;8.52)	<0.001†	1.43 (0.88;2.30)	0.147
Cancer (metastatic, solid tumor or lymphoma)	5.16 (3.69;7.23)	<0.001†	1.58 (1.09;2.26)	0.014†
Other Neurological Disorders	3.00 (1.64;5.53)	<0.001†	0.69 (0.37;1.27)	0.240
Paralysis	1.42 (0.19;10.04)	0.718	0.87 (0.15;4.70)	0.872
Psychoses	2.46 (1.46;4.14)	<0.001†	1.05 (0.60;1.83)	0.862
Pulmonary Circulation Disorders	1.48 (0.54;4.18)	0.447	1.01 (0.38;2.64)	0.978
Rheumatoid Arthritis	4.49 (2.76;7.34)	<0.001†	1.06 (0.62;1.78)	0.821
Valvular Disease	1.03 (0.60;1.73)	0.912	1.02 (0.60;1.73)	0.928

CI, confidence interval; ER, emergency room; IP, inpatient; OHA, oral hypoglycemic agents; OR, odds ratio (an OR >1 shows that the potential cost driver increases the patient risk of being in the high cost cohort).

*If two patient characteristics were highly correlated with one another, only one was kept in the model, in order to prevent co-linearity. The Deyo-Charlson comorbidity score was excluded as a potential factor in this analysis, in order to observe the individual effects of specific comorbidities. Given that there are only 10 study subjects with AIDS and that all these patients are in the high all-cause cohort, the effect of AIDS is not estimated in the all-cause cost model.

†The effect of the covariate on the odds of incurring high costs was statistically significant at p < 0.05.

‡Include comprehensive, CDHP, and HDHP plans, which together accounted for <10% of sample.

Table 4. Inpatient admission related to a complication of diabetes, breakdown by type of admission.

		Estimates from adjusted* logistic and linear regression models
Modeling of IP admission in three alternative models (any vs none)	n (%) (of 4104 patients in	All-cause costs		Diabetes-related costs
	study sample)	OR^† (95% CI)	Cost differences^‡, $ (95% CI)	OR^† (95% CI)	Cost differences^‡, $ (95% CI)
Model 1: main analysis
Inpatient admission related to a complication	228 (5.6)	13.54 (8.14;23.57)^§	+32,200 (29,275;35,125)^§	9.69 (6.31;15.08)^§	+15,012 (13,570;16,453)^§
Model 2: IP admission variable from main analysis was replaced by specific categories of IP admission
IP admission for microvascular complications	78 (1.9)	9.02 (2.87;40.36)^§	+18,801 (13,911;23,692)^§	1.75 (0.82;3.82)	+8,691 (6,293;11,088)^§
IP admission for macrovascular complications	159 (3.9)	13.36 (7.02;27.45)^§	+30,366 (26,871;33,861)^§	5.55 (3.35;9.30)^§	+11,466 (9,753;13,180)^§
IP admission for non-vascular complications	70 (1.7)	9.50 (3.32;31.76)^§	+18,900 (13,823;23,977)^§	16.24 (6.72;43.12)^§	+15,640 (13,151;18,129)^§
Model 3: IP admission variable from main analysis was replaced by specific diagnoses related to IP admission^‖
IP admission for nephropathy complications	53 (1.3)	4.96 (1.29;32.98)^§	+16,107 (10,106;22,108)^§	0.83 (0.35;2.05)	+3,241 (356;6,126)^§
IP admission for neuropathy complications	30 (0.7)	21.93 (3.84;418.93)^§	+12,856 (5,489;20,222)^§	25.23 (4.58;473.95)^§	+14,269 (10,727;17,810)^§
IP admission for atherosclerosis, aneurysm, or embolism complications	12 (0.3)	–	+23,035 (11,704;34,366)^§	3.24 (0.64;19.75)	+16,148 (10,700;21,595)^§
IP admission for peripheral vascular conditions complications	36 (0.9)	1.65 (0.47;6.81)	+21,725 (14,517;28,933)^§	0.91 (0.29;2.93)	+2,189 (−1,276;5,655)
IP admission for cerebrovascular disease complications	37 (0.9)	11.53 (3.08;57.17)^§	+12,817 (6,047;19,586)^§	4.72 (1.78;12.73)^§	+995 (−2,260;4,250)
IP admission for coronary artery disease complications	108 (2.6)	11.86 (5.53;28.66)^§	+26,803 (22,736;30,869)^§	4.83 (2.74;8.68)^§	+11,965 (10,009;13,920)^§
IP admission for infections (urinary tract infection, kidney infection, mycoses) complications	27 (0.7)	6.52 (1.40;35.89)^§	+30,547 (23,011;38,082)^§	11.16 (3.51;37.70)^§	+12,807 (9,184;16,430)^§
IP admission for ulceration or diabetic bone changes complications	12 (0.3)	–	+609 (−12,798;14,016)	0.85 (0.07;20.84)	−11,296 (−17,742;−4,850)^§
IP admission for hypoglycemia complications	22 (0.5)	–	+11,839 (1,751;21,928)^§	–	+29,278 (24,427;34,128)^§
IP admission for unspecified diabetes-related complication complications	19 (0.5)	14.79 (2.20;299.02)^§	+11,561 (2,407;20,716)*	30.30 (5.11;584.56)^§	+15,359 (10,958;19,761)^§

CI, confidence interval; IP, inpatient; n, number; OR, odds ratio.

*Models are adjusted for all covariates from the main model. In Models 2 and 3, the logistic regression model from the main analysis was replicated by replacing the IP admission related to a complication of diabetes by either specific categories of IP admissions (i.e., microvascular, macrovascular, and non-vascular complications [model 2]) or by the specific diagnoses associated with IP admissions (e.g., nephropathy, neuropathy, hypoglycemia [model 3]). Then, the logistic regression models 2 and 3 were replaced by linear models in which the dependent variable was a continuous measure of total cost per patient during the 1-year study period, while the independent variables remained the same as in models 2 and 3. The estimates yielded by the linear model represent the incremental costs associated with each specific complication of diabetes.

^†An OR >1 indicates that patients with any given type of admission were more likely to have high costs (i.e., quartile 4).

^‡Cost difference is an incremental annual total cost of patients with any given type of admission.

^§The complication of diabetes had a statistically significant effect on incurring high costs at p < 0.05.

^‖Diagnoses affecting few patients were excluded from some regression models to avoid non-convergence.

U.S. Centers for Disease Control and Prevention. National Diabetes Fact Sheet: national estimates and general information on diabetes and prediabetes in the United States, 2007. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2007. p 1-8. http://www.cdc.gov/diabetes/pubs/factsheet07.htm. Accessed March 13, 2013

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