Thyroid autoimmunity in Type 2 (non-insulin-dependent) diabetic patients of Caucasoid, black and Mexican origin

Diabetologia, Jul 1984

S. Kasim, A. Bessman

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Thyroid autoimmunity in Type 2 (non-insulin-dependent) diabetic patients of Caucasoid, black and Mexican origin

Diabetologia Thyroid autoimmunity in Type 2 (non-insulin-dependent) diabetic patients of Caucasoid, Black and Mexican origin S. K a s i m 0 A. Bessman 0 0 Rancho Los Amigos Hospital, Universityof Southern California School of Medicine , Downey,California , USA Summary. Four hundred and forty-nine patients with Type 2 (non-insulin-dependent) diabetes mellitus and 270 control subjects from Caucasoid, Mexican and black origins were screened for the presence of thyroid microsomal antibodies. Mexican female control subjects had a significantly higher frequency of thyroid microsomal antibodies when compared with black female controls (21% versus 6%, p < 0.01). Type2 diabetic patients did not have a higher frequency of thyroid microsomal antibodies when compared with their sex- and race-matched control counterparts. The subgroup of diabetic patients who required insulin for the control of their blood glucose did not have a higher frequency of thyroid microsomal antibodies when compared with non-insulin-requiting diabetic patients. In conclusion autoimmunity against thyroid gland, as manifested by thyroid microsomal antibodies, is not more common in Type 2 diabetic patients when compared with sex- and race-matched control subjects. Type 2 diabetes; thyroid microsomal antibodies; race - 9 Springer-Verlag1984 I n f o r m a t i o n regarding the relationship b e t w e e n Type 2 diabetes a n d a u t o i m m u n i t y is very limited. A previous study which d e t e r m i n e d thyroid microsomal a n t i b o d y (TMA) status in M e x i c a n A m e r i c a n patients with Type 2 diabetes r e p o r t e d a 2.8% prevalence [ 1 ]. O t h e r studies r e p o r t e d 9.2% a n d 9.1% frequencies o f thyroid antibodies in Type 2 diabetes, which were similar to the f r e q u e n c y seen in control subjects. In these reports the majority o f the patients were C a u c a s o i d but the distrib u t i o n o f T M A according to sex was not specified [ 2, 3 ]. The f r e q u e n c y o f thyroid antibodies in black Type 2 diabetic patients is u n k n o w n . A s u b g r o u p o f patients with Type 2 diabetes require insulin for control o f their b l o o d glucose levels. T h e r r l e o f a u t o i m m u n i t y in insulin-requiting versus non-insulin-requiting diabetic groups m a y be different. T h e freq u e n c y o f autoantibodies in these subgroups o f Type 2 diabetic subjects is also not known. Even for n o r m a l subjects there is no available study c o m p a r i n g the freq u e n c y o f thyroid antibodies in the different races and sexes o f the same population. In this study we d e t e r m i n e d the f r e q u e n c y o f T M A in male and female n o r m a l subjects and insulin-requiring and non-insulin-requiring Type 2 diabetic patients o f Caucasoid, black and M e x i c a n origin. Subjects and methods Subjects Rancho Los Amigos Hospital is a Los Angeles County facilitywhich provides health care for medically indigent patients. Two hundred and seventynormal subjects who attended Rancho Los Amigos Hospital Employee Health Servicefor their pre-employmentphysical examinations participated in the study. Four hundred and forty-nine diabetic patients who regularly attended the diabetic outpatient clinics for at least 6 months before the study were also recruited after a medical history was taken and a physical examination was carried out. Insulin-treated patients were carefully questioned about the mode of onset of diabetes and previous ketoacidotic episodes. Those patients who had medical histories compatible with TypeI (insulindependent) diabetes were excluded from the study. The majority of non-insulin-requiringpatients were treated with diet and oral hypoglycaemicagents. The number of patients who were treated with diet alone ranged between two to eight in each subgroup. Patients with previously diagnosed thyroid disease were excluded since the objective of the study was to determine the previously undetected thyroid pathology in diabetic patients. Patients with co-existentautoimmune disease, such as rheumatoid arthritis, systemic lupus erythamatosus, etc., were also excluded.A portion of sera obtained for other required testing was utilized for this study after obtaining verbal consent. Thyroid microsomal and thyroglobulin antibody testing The antibodies were measured by the red cell haemagglutination method [ 4, 5 ].A positivereading was defined as the presence of either Black subjects Mexican subjects Female 30 +_ 9 (n = 50) 64 +_14 (n = 59) 64 + 9 (n = 23) Male 37 _ 12 (n = 50) 62 _+15 (n = 36) 69 + 13 (n = 13) Female 39 +_13 (n = 43) 62 +_13 (n = 39) 56 + 11 (n = 21) Male 34  11 (n = 27) 61 + 11 (n = 51) 66 +_ 8 (n = 23) Results are expressed as mean + SD. n = number of subjects studied in each group Control subjects All diabetic patients Insulin-requiting patients Non-insulinrequiting patients a p < 0.01 when compared to black female control subjects antibody at a titre of 1/100 or more diluted serum sample. Statistical analyses were performed using the Z 2test. Control subjects The relative frequencies o f thyroid microsomal and thyroglobulin antibodies The sera obtained from the first 140 subjects were tested for both antibodies. Twenty-nine subjects had anti-microsomal antibodies. Among those, 13 (45%) also had thyroglobulin antibodies. In one subject the thyroglobulin antibody titre was higher than the microsomal antibody titre (1/320 and 1/160, respectively). There was no serum sample which was positive for thyroglobulin antibody but not for microsomal antibody. For the rest of the study subjects, thyroglobulin antibody was tested only if the microsomal antibody was positive in the serum sample. Twenty-nine percent of these samples were also positive for thyroglobulin antibodies. Titres of each antibody ranged between 1/160 to 1/10240. Since the number of subjects who had both antibodies was small in each subgroup, the results are not reported separately. The age distribution of the study subjects is shown in Table 1 and the frequencies of thyroid microsomal antibodies are summarized in Table 2. When the differences between sexes in the same race and the differences among the races in the same sex were compared, the only significant difference was between the Mexican and black females: the prevalence of T M A was 21% in Mexican and 6% in black females (p < 0.01). However, Mexican female control subjects were significantly older than black female controls. When the data were re-analyzed to compare a randomly selected agematched subgroup of black female controls with Mexican female control subjects, the difference still remained significant (p < 0.025). Patients with Type2 diabetes The diabetic patients were significantly older than their sex- and race-matched control counterparts. When the prevalence of the antibodies in the diabetic subjects were compared to the sex- and race-matched control subjects the differences were not significant. Insulin-requiring versus non-insulin-requiring diabetic patients no relationship between T M A and the m o d e of treatment required for the control of blood glucose. Insulin-requiring patients were usually treated with a single injection of intermediate acting insulin alone or in combination with a short-acting insulin. The patients were free of ketonuria. The prevalence of T M A was not significantly greater in insulin-requiring patients when compared with the sex- and race-matched non-insulinrequiring diabetic or control subjects. Discussion The frequency of thyroid antibodies has been reported as 2%-20% in the general population [ 6-8 ]. The prevalence of T M A is generally lower a m o n g Caucasoid males (3%-10%) than Caucasoid females (12%-20%). We are not aware of any reports of the frequency of T M A a m o n g Mexican and black control subjects o f the different sexes. Our study indicates that the lower frequency of T M A f o u n d a m o n g black diabetic subjects is also observed in the black control population; this agrees with the concept that black subjects are less susceptible to organ-specific autoimmunity [ 9 ]. The prevalence o f T M A a m o n g Type 2 diabetic patients was not significantly higher than in their non-diabetic counterparts. Riley et al. reported that the frequency of T M A shows a major increase after the fifth decade of life [ 10 ]. The diabetic patients in this study were significantly older than the control subjects; despite that, t h e y did not have a significantly higher frequency of TMA. Previous studies indicate that Type 2 diabetic patients with positive islet cell antibodies are likely to develop insulin deficiency and require insulin [ 11 ]. In our study we searched for a possible relationship between T M A and requirements for insulin for the control of blood glucose. Caucasoid insulin-requiting diabetic patients, both male and female, tended to have a higher frequency of T M A than non-insulin-requiting diabetic patients and Caucasoid control subjects but these differences were not significant. In conclusion, Type 2 diabetic patients did not have a higher frequency of T M A when compared with their race- and sex-matched control counterparts. There was Acknowledgements.We would like to thank Ms. W.Talbott for referral of the control subjects, Ms. V.Boren for typing the manuscript, and Ms. H. Ostegaard for technical assistance. 1. Zeidler A , Frasier DS , Penny R , Stein RB , NicoloffJT ( 1982 ) Pancreatic islet cell and thyroid antibodies, and islet cell function in diabetic patients of Mexican American origin . J Clin Endocrinol Metab 54 : 94 % 954 2. Fialkow PJ , Zavala C , Nielson R ( 1975 ) Thyroid autoimmunity: increased frequency in relatives of insulin-dependent diabetes patients . Ann Int Med 83 ( 2 ): 170 - 175 3. GrayRS, lrvineWJ, Taft AD , Seth J , CameronHD, Clarke BF ( 1979 ) Unrecognized thyroid failure in diabetes mellitus . J Clin Lab Immunol 2 : 221 - 224 4. Witebsky E , Rose NE , Terpeon K ( 1957 ) Chronic thyroiditis and autoimmunization . JAMA 164 : 1439 - 1447 5. WitebskyE, Rose NR , Paine GR ( 1957 ) Thyroid specific antibodies . Ann NY Acad Sci 69 : 669 - 677 6. Basteine PA , Van Haelst L , GoldsteinJ ( 1977 ) Asymptomatic autoimmune thyroiditis and coronary heart disease . Lancet 2 : 155 - 158 7. BasteinePA, Neve P , BonnynnsM ( 1971 ) Preclinical hypothyroidism: a risk factor for coronary heart disease . Lancet 1 : 203 - 205 8. TannerAR , Scott-Morgan L , Mardell R , Lloyd RS ( 1982 ) The incidence of occult thyroid disease associated with thyroid antibodies identified on routine antibody screening . Acta Endocrinol (Copenh) 100 : 31 - 35 9. Neufeld M , Maclaren NK , Riley WJ , Lezotte D , McLaughlin JV , SilversteinJ, RosenbloomAL ( 1980 ) Islet cell and other organspecific antibodies in US Caucasians and blacks with insulin-dependent diabetes mellitus . Diabetes 29 : 589 - 592 10. Riley WJ , WinerA, Goldstein D ( 1983 ) Coincident presence of thyrogastric autoimmunityat onset of Type 1 (insulin-dependent) diabetes . Diabetologia 24 : 418 - 421 11. ReavenGM ( 1980 ) Autoimmunity and diabetes mellitus . In: Podolsky's clinical diabetes: modern management . AppletonCentury Crofts , New York, pp 30 - 33 Received: 26 October 1983 and in revised form: 13 March 1984

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S. Kasim, A. Bessman. Thyroid autoimmunity in Type 2 (non-insulin-dependent) diabetic patients of Caucasoid, black and Mexican origin, Diabetologia, 1984, 59-61, DOI: 10.1007/BF00253504